CHAPTER FIFTY SEVEN
an honest mistake.
season five, episodes
fifteen and sixteen.
author's note — in honor of coding
hitting 1 million reads, grab a snack,
settle in, and get ready for this long
emotional rollercoaster!
tw: panic attacks, violence
CASSIE SAT WITH GEORGE ON THE BENCHES IN FRONT OF THE HOSPITAL, A BAG OF CHIPS BEING SHARED BETWEEN THEM AS THEY TOOK THEIR BREAK TOGETHER. It was a nice day out, leaves falling from the trees and creating a pathway of oranges and reds towards the hospital doors.
Cassie reached into the bag, her head snapping up as George slapped her hand away. "What?"
"You keep taking all the good ones," George pouted, taking the chip she was originally reaching for. "See, this one has all the cheese. I keep getting stuck with the empty ones."
Cassie lightheartedly rolled her eyes, shoving the chips in his direction. "Whatever, I was done anyways." She glanced up, smiling at Lily as she approached them. "Blair!"
George looked up as well, grinning as his girlfriend waved hello. "Hi Dr. Harper," Lily said, moving to stand in front of George. "And hello to you too, handsome."
He held the bag of chips out in question. "Want a dorito?" Lily shook her head, snorting fondly at the man she'd grown to love.
"No, I'm okay. I actually have a surgery in a few minutes, but I just figured I'd stop to confirm our plans for tonight?"
"Oh, our plans," George nodded slowly, trying to act nonchalant but failing miserably. "Our very normal plans, which are normal." Cassie and Lily shared a weird look, the latter laughing awkwardly as she cleared her throat.
"So, um, meet you at Joe's after our shift?"
"Yeah, yeah, Joe's. Definitely just Joe's."
"Okay then," she gave George a strange look, kissing him on the cheek and heading inside. Cassie watched amusedly as George leaned back in his seat, attempting to appear normal as he stared lovingly at his retreating girlfriend.
Once he was completely sure Lily was out of hearing range, George lost all composure, turning to Cassie with a level of excitement she'd rarely seen. "Okay, I'm going to tell you something, and you have to promise to keep it a secret."
Cassie narrowed her eyes. "Is it a good something, or a bad something?"
"Good," he replied instantly. "Well, I hope so, at least. Depending on your reaction."
"Okay, I promise."
George scanned his surroundings, before leaning into Cassie's personal space. She copied the action, mocking him slightly but secretly invested in what made him act so strangely. He held a dramatic finger to his lips in a hush motion, making her roll her eyes and slap his hand away. George gave her a deadpan look, to which she returned with a gesture of get on with it already.
He took a diamond ring from his pocket, mirroring Derek's actions from the day before. Cassie froze, raising a single brow in question.
"I'm going to propose," George whispered, a hesitant smile on his face as he awaited her reaction. "Tonight."
Cassie's jaw dropped to the floor.
"You—" she stuttered, unable to form a coherent sentence. Taking the ring from his hands, she gazed down on the emerald green diamond the size of her pinky nail.
George furrowed his brows in slight concern. "Say something? Preferably, something other than you're an idiot, O'Malley, because Dr. Bailey already said that this morning, and I really don't want to go through that again."
When Cassie moved her gaze upwards, George was taken aback by the unshed tears lingering in her eyes.
"You're getting married?" she asked in a high pitched tone, despite her voice coming out as just louder than a whisper. "To Lily?"
"She has to say yes first, but yeah, that's the plan." He took the ring back, taking her hand in his own in the process. "I know you probably think I'm crazy, and that it's way too soon, but it feels right. I love her, and I want to spend the rest of my life with her." He searched her eyes, looking for a way to tell how she was feeling. "And, if you're up for it, I'd like you to be my best man. Or woman, or whatever."
Cassie's lip wobbled for a moment, before she promptly burst into tears.
"Oh, no," George shook his head rapidly. "Oh, please don't cry, please don't cry!" Cassie continued bawling, making him cringe as he waved uncomfortably to the people passing by. "I'm sorry! You know what? Nevermind, it was a bad idea anyways! Okay?" Cassie continued to sob. "I'm sorry!"
"Sorry?" Cassie repeated through a fit of tears. "Why are you sorry?"
"I-I made you cry."
Cassie laughed through a choked sob, throwing her arms around his shoulders and hugging him tightly. "I'm going to be a best man!" she cheered, her tears falling onto his scrub top. "Everyone's getting married! This is like, the best week ever!" She pulled away, an excited grin on her face. "Oh my god, I need to go buy a tux! Okay, what are you thinking, black or red? Ooh, maybe purple!"
A soft smile grew on George's face as he pulled her into another hug, digging his head into her shoulder. "God, you have no idea how much I love you."
Cassie shook her head, thinking there was no possible way that George loved her more than she loved him.
"I think I have some idea."
The moment was cut short when Cassie's pager went off. As she checked it, a deep frown grew on her face. She looked back to George apologetically, before wordlessly rushing into the building.
☆
Cassie ran into Mark outside of Addison's brother's hospital room, holding her pager in the air as she spoke. "Archer is here? In the hospital?" she questioned, earning a nod from her boyfriend.
"Worms in the brain, if you can believe it," Mark shook his head in disbelief, before pausing once he got a good look at her. "Have you been crying?"
"Don't worry," she waved him off. "They were happy tears."
"Okay, well, I was just about to head in there," he pointed to the room. "Want to join me?"
Cassie winced. "Oh, no, I really don't think I should—" Mark rolled his eyes, grabbing her arm and bringing her towards the room despite her silent protests.
"Our eyes met over the cadaver," Cassie heard a voice singing, recognizing it as belonging to Addison's friend Naomi, who she'd met many times before. "And I knew I had to have her!" Cassie and Mark approached the room, hearing Naomi laugh as she teased Addison. "What was the next line?"
"Can we talk about something else?" Addison said lowly, not-so-subtly eyeing Meredith in the corner of the room.
Archer smirked at his sister, continuing the song. "Had his mitral valve grown too thick?" he laughed, as Naomi continued the teasing.
"Is that what made our cadaver so sick?"
Mark grinned, entering the room and trying to pull Cassie with him. She refused, standing behind him to avoid being seen. "Greatest love song of all time," he laughed. The group greeted him warmly, too focused on his presence to notice Cassie. "Did you guys get to the part where Derek rhymes gross anatomy class with Addison's fine ass? Because I wrote that line."
They all laughed, as Cassie took a big step forward and finally made herself known.
"Actually, if I recall correctly, your lyrical genius had some help." At Addison's glare, she looked to the right, spotting a wildly uncomfortable Meredith sitting in the corner. Mark followed her gaze, cringing.
"Oh, my bad."
"No, no, it's fine," Meredith smiled. "I, uh, I think it sounds like a... fine song."
"Cassandra Harper," Archer sighed, his face dropping slightly. "It's been a while."
"It has."
Archer raised a brow. "How have you been?"
Cassie took a deep breath, moving to the edge of the bed. Her lips twitched upwards as she crossed her arms, tilting back and forth on the balls of her feet. "Better than you, clearly."
Archer shook his head, laughing somewhat bitterly. "Actually, as it turns out, worms in the brain hurts surprisingly less than a broken nose and a grade three concussion."
Everyone in the room went awkwardly silent, other than Meredith, who frowned at her person in confusion. "Cass, what's he talking about?"
Mark cleared his throat, saving Cassie from having to answer. "So, uh, Archie, I heard you were gonna let Derek remove those little suckers from your brain." Cassie sent him a thankful look, to which he returned with a wink.
"Maybe."
"He is," Addison and Naomi chorused.
"I hate surgery, especially brain surgery," Archer argued.
"Yeah," Mark nodded in faux understanding. "Being a neurologist, you probably see a lot of patients post-op who are just, you know, scrambled eggs up there—"
"Okay, you know what, Mark? You're not helping right now," Addison interrupted. "We're sitting here, trying to convince him that surgery is—"
"Not an option."
Cassie cringed at the sound of Derek's voice as he entered the room, peeking one eye open to see Archer's glare as he turned to Meredith.
"That," Archer pointed to Derek, "is what I was talking about."
Cassie tilted her head. "We don't need to—"
"You're still on that?" Derek scoffed, knowing exactly what he was referring to without even trying. "It was one punch, five years ago. Get over it."
Meredith raised a brow at Cassie, prompting her to explain. "Derek punched Archer because he was looking at me while I was wearing a bikini," Cassie said, feeling awkward with everyone's eyes on her. She turned to narrow her eyes at Derek. "While we were at the beach."
"You were eighteen—"
"I was a fully grown adult—"
"Oh, please," Derek rolled his eyes. "You were a child, and you still are!"
"Shut up!" Addison shouted, stunning them into silence. "Just shut the hell up! God, my brother has worms in his brain, and you're fighting over something that no one freaking cares about!" She huffed loudly, crossing her arms over her chest as she turned her attention to Derek. "So just shut up, and tell us what the scans showed."
Derek nodded, not without sending Cassie a look. "According to these scans, the single cyst that you had in your last CT has now multiplied by eight, all clogging the third ventricle. There's no way I can surgically navigate through a mess like that without rupturing one."
Addison frowned. "So what does that mean?"
Everyone stood silently, exchanging knowing glances with downcast expressions.
"You're in a room full of doctors, Addison, who are all being very quiet right now." Archer took her hand in his own. "I'm gonna die. That's what it means."
☆
Cassie and Meredith exited the room together, the latter smirking slightly. "Okay, explain this to me. Archer looks at you, while you happen to be wearing a bikini, and Derek beats him up? Just like that?"
"He didn't beat him up, he punched him," Cassie corrected. "It's different."
Meredith gave her a deadpan look. "There has to be more to it than that."
Cassie bit the inside of her cheek, trying to figure out a way to tell her without actually telling her.
"It's just—" she took a deep breath, trying to find the words. "It happened right after I turned eighteen. And a few months before, when I was still a kid, um, something happened to me that scared him."
Meredith frowned in concern. "What—"
"It's nothing," she shut her down immediately. "I just... I got hurt, is all."
"Okay, but I mean, why does he act like that?"
"He still sees me that way," Cassie shrugged. "As a child, who needs someone to protect her. He just can't get it through his head that I'm an adult now, and I can be on my own and make my own choices without needing him to constantly hover over my shoulder."
Meredith thought for a moment. "That's why you haven't told him about Mark."
"The opposite, actually. That's why I want to tell him. So he'll finally understand."
Meredith raised a brow in understanding, looking up to see Mark, who stood only a few feet away, and unintentionally heard the entire conversation. "Cass," she nodded in his direction, smiling softly. Cassie turned around, as Meredith left to give them some privacy.
"You weren't supposed to hear that."
Mark frowned deeply, guiding her into an empty exam room and shutting the door. "Why didn't you tell me that's how you felt?"
Cassie shrugged, not really knowing the answer. "I tried. Well, sort of. You didn't want to tell him, and I just figured we'd wait until you did."
Mark sighed heavily, leaning against the edge of the exam table. He observed Cassie, who simply watched him become lost in thought. Several long seconds later, he reached out, pulling her forward so she was standing between his legs. He smiled down at her, causing her to instinctively return the action, despite being a bit confused.
"Let's do it," he said confidently. "Let's tell Derek about us."
Slowly, a grin grew on Cassie's face. "You're sure?"
"I'm sure," Mark repeated, laying a soft kiss on the tip of her nose. "I love you, angel, and I want my best friend to know. Hell, I want everyone to know."
"Okay," Cassie breathed out, biting her lip to restrain her grin. "We're really telling him?"
Mark smiled. "We're really telling him."
☆
"So basically, you'll grab each one of the cysts with forceps, pull it up to the edge of the port, and then suction the fluid?" Cassie gaped, staring in awe at Derek as he explained a way to save Archer's life.
"Exactly," Derek nodded, looking closely at the scans. Cassie shook her head, following his lead and memorizing each part of the x-ray. "And you're scrubbing in."
Her gaze snapping upwards, Cassie furrowed her brows in disbelief. "I'm not sure that's—"
"Look," he interrupted, wearing a slightly guilty frown. "I'm sorry for what I said in there." Cassie opened her mouth to respond, but he cut her off. "You're not a child, Cass."
Cassie smiled softly. "Thank you for apologizing, but it's really okay. Just, maybe save the protective big brother mode for when we're not at work?"
"Well, it's not completely my fault," Derek defended himself. "There's no way I'm going to let a man the same age as me look at you the way Archer did. It's creepy, and just plain wrong."
Cassie's eyes widened slightly, the knowledge that Mark was a full year and a half older than Derek eating away at the back of her mind.
Maybe Mark was right before, and they should wait for a while before telling him about their relationship.
"So," Derek's voice snapped her out of her thoughts. "Will you scrub in? I can get the Chief to put you on my service for the week."
"Yeah," she nodded distractedly, anxiously fiddling with the hem of her scrub top. "Yeah, sure."
☆
After several hours spent in surgery on Archer's brain, which ended up being wildly successful, Cassie was on her way to take a mid-shift shower in the locker room, when the sound of footsteps sprinting down the hall gained her attention.
George ran quicker than he ever had, a grin taking up his entire face as he made a beeline for his best friend. Cassie stared with wide eyes as he came to an abrupt halt in front of her, pulling at the collar of the fancy suit he was wearing to gain oxygen.
He panted momentarily, taking a huge gulp of air, before shouting at the top of his lungs, "SHE SAID YES!" Cassie gasped, a hand slapping over her mouth at the words. "She... she said... oh, wow, is it just me, or is it really hot in here?"
"She said yes?!" Cassie smiled, looking behind him to see if his fiancée was following at a slower pace. "That's amazing! Where's Lily?"
Suddenly, George froze, before a terrified expression came over his face.
"CRAP, I FORGOT LILY!"
He turned on his heel, racing back to Joe's, where he'd left Lily immediately after she said yes to his proposal, in too much of a rush to tell Cassie the good news.
Cassie watched him go, happy, but incredibly confused. "Congratulations?"
☆
Fresh out of the shower and in clean scrubs, Cassie made her way to check on Derek's post-ops while he and the rest of the New Yorker's went out for drinks. She was invited, but had to decline, since her shift still had another ten hours left.
As she was sorting files and updating charts at the nurses station in the neuro wing, she heard a machine from one of the rooms begin to beep rapidly, causing her to jump to her feet.
Cassie ran into Alex as she entered the room, recognizing the patient as Jen, a pregnant woman Derek and Alex had operated on that day.
"What's happening?" Cassie asked urgently, seeing how Jen was having a seizure. "I didn't see any notes in her chart, why is she seizing?"
"I have no idea," Alex admitted, having to shout over the cries of Jen's husband, who was pacing back and forth out of fear.
"What's going on?!"
Alex and Cassie shared a look, before yelling to the nurses in unison. "Page Shepherd, now!"
☆
THREE DAYS LATER
"Is he still beating himself up?" Alex asked Cassie and Meredith, who stood together outside of Jen's room. "Addison says he's still beating himself up."
"What?" Cassie frowned, looking into the room where Derek was laughing with Jen and her husband. "What the hell are you talking about?"
"Alex," Meredith sighed.
He ignored her, giving Cassie a deadpan look. "The head of neuro hasn't left his patient's bedside for three days. He messed up in her first surgery, and now he's trying to cover his ass."
Meredith rolled her eyes. "He's fine, and I thought Addison was leaving?"
Cassie shook her head. "She put Archer on a plane back to LA last night. I think her flight leaves in a few hours, Mark's driving her to the airport right n—"
"Cass," Derek interrupted from the doorway. "Call Addison, tell her I need her to stay."
"You got it," she nodded, turning back to the other two in question. "Is something wrong with Jen's baby?"
Alex shook his head with a scoff in Meredith's direction. "Like I said, he messed up."
☆
Mark took a deep breath, before opening up the doors to the computer room Derek was in after the surgery on Jen. They placed a patch in her brain, hoping it fixed the problem despite an argument he and Addison had in the process.
"There he is," Mark clapped, an overly enthusiastic edge to his voice. "The legend himself! How are you, legend?"
Derek laughed, not taking his eyes off the computer screen. "Are you drunk? Should I be worried about you?"
"And he's got his sense of humor back," Mark grinned. "How's your patient?"
"She's good. Stable." He turned around to face him. "You know, today's the first day in a long time that I remember what it feels like to be good at my job."
Mark scoffed, waving a dismissive hand in the air. "You? Come on. You're like the Dalai Lama of surgery. People from all over the world come here to let you cut into them, and you know what else? You look good doing it." Derek gave him a weird look, but he continued. "I like the facial hair, by the way. Keep it that length, no more, no less."
"Okay, okay, all right, stop," Derek shook his head with a snort. Mark sighed heavily, shifting in his seat out of nerves.
"Derek, there's something that we need to discuss."
"Go ahead and have sex with Addison."
"Addison?" Mark frowned. "What?"
"Go for it," Derek nodded nonchalantly. "Seriously, I don't mind."
Mark subtly bit the inside of his cheek to keep in his anger at the fact that his best friend thought so low of him. "I don't want to have sex with Addison."
"Really? Well, what did you want to discuss?"
Mark stared at Derek for a long moment.
"Nothing."
☆
"Tell me why I shouldn't go to the Chief."
Cassie didn't look up, keeping her head in her chart as she failed to answer Addison's question.
"Well, hello to you too."
"Cass," Addison sighed, crossing her arms over her chest like a disappointed mother. "He made a mistake in Jen's first surgery, and it's led to a series of complications."
"I wasn't even there for her first surgery."
"No, but you're here now," she argued. "You really don't see it? He is way too close to this patient to be healthy."
Cassie finally looked up, seeing how worried Addison actually was. Sure, Derek seemed a little on edge, but it was nothing Cassie hadn't seen before with his other patients. "I'm not going to worry until there's something to worry about," she shrugged. "Trust me, Addie. Everything will be fine."
Addison thought for a moment, before giving up with a roll of her eyes. "Fine. But when that time comes, and it will, you need to tell me when."
"Okay, but really, Jen is—"
Cassie and Addison's pagers went off in unison, interrupting their conversation. Addison looked down to her pager, and back to Cassie as she finished her sentence for her.
"—being taken into the OR as we speak."
☆
In surgery with Derek, Cassie stood on his right as Meredith stood on his left. Addison and Alex took their place at the other end of the table, monitoring the stats for Jen's baby. The patch in Jen's brain, which Derek had placed earlier that day, had blown, and now he was trying to find a way to fix it.
"The swelling's not going down," he muttered in frustration. Cassie noticed the sweat on his forehead and his furrowed brows, giving him a concerned look as he spoke.
"Maybe the ventriculostomy is plugged," Meredith suggested, sending her boyfriend a similar expression.
"No," he said, switching out his tools. "Damn it!" Everyone paused to look at him, as he stared blankly at Jen's brain for several long seconds. Cassie made eye contact with Addison, quickly looking away before the woman could see the worry in her eyes.
Cassie looked up at her brother, willing him to do something, anything. "Derek?"
Derek shut his eyes tightly, opening them as he spoke. "I have to take out the temporal lobe."
Alex sent a look to Addison from his place by the baby monitor as he asked, "Won't that kill her?" Cassie took a deep breath behind her mask, shaking her head at his question.
"No," she answered, reciting almost word for word what she'd read in a textbook back in med school. "But, removing the temporal lobe had been shown to have some pretty serious defects, like loss of speech, voice, and... um, and loss of memory—"
"The brain can rewire," Derek insisted. "I've done it before to stop seizures."
Meredith raised a brow, asking what everyone in the room was thinking. "Have you done it before for this?"
It was silent for a moment.
"I'm doing it now."
☆
"She's bleeding into the frontal lobe," Cassie heard Derek say to himself, sharing a worried look with Meredith. "Now, if I can just stop the bleed, save the rest of the brain, she'd have a chance."
Addison frowned at the baby's heart monitor. "Decels are getting longer. Derek, I have to deliver the baby."
"No," he shook his head. "She... just... she's lost too much blood. If you cut her now, she'll bleed out. I can save her."
"How?"
Derek thought to himself for a long time, causing Cassie's anxiety to rise even further.
"I have to cut out the frontal lobe."
Eyes going wide, Cassie looked to Addison in panic. "When!" she blurted, referring to their earlier conversation. Addison stared at her, nodding quickly in understanding as she stuttered over her words.
"D-Derek, no," Addison held a hand up in the air, raising her voice. "Stop! Derek, you've done enough."
"Her frontal lobe?" Meredith said slowly. "Can she live without her frontal lobe and her temporal lobe?"
"Yes," Derek replied, at the exact same time as Cassie said, "No."
Derek turned his head to send his sister a glare, ignoring what Addison had to say. "No, Derek, she can't! Listen to me. This baby is not getting any oxygen now. I know that you want to save Jen, and I know you feel like you have to, but not this way!"
"I can do this," Derek insisted, his volume rising. "I can save them both. She will live."
"Not as the person that her husband and child need her to be! She'll lose everything about her that makes her human." Addison kept her gaze on Derek, who refused to reply. She looked to Cassie for help, only to see her eyes stuck onto the side of Derek's face, her posture completely rigid. "Meredith?"
"Are you sure you can do this?" Meredith whispered quietly.
"I have no choice. Bipolars."
"The baby's heart rate is bottoming out," Alex informed them.
"Damn it, Derek! Okay, damn it. We've gone... this has gone too far. Taking the frontal lobe out, even if she does live, you are creating a monster! You don't get to play god here, Derek! Jen is gone, but this baby has a chance to live. You need to let her go. Let it go."
Cassie watched as Derek continued to work.
"Derek?"
"That's it," Addison scoffed, throwing her arms in the air in frustration. "I'm taking the baby out."
"Put down the scalpel, Addison!" Derek shouted, making Cassie freeze. She really hated it when he yelled.
Addison didn't move an inch, the scalpel hovering just an inch above Jen's stomach.
"You put down the scalpel."
"Addison, put the scalpel down!"
"You put the scalpel down! You have to let her go—"
"Take your hand off the scalpel, Addison!" Derek screamed, silencing the entire OR.
Cassie wanted to say something, but the words were lodged in the back of her throat. She'd seen him angry, and she'd seen him yell, but this was different.
In that moment, Cassie was actually scared of Derek. Her brother. She felt unsafe, like she was the patient on the table instead of Jen. Her breathing noticeably sped up, her hands and feet tingling in numbness as she became lightheaded and black spots clouded her vision.
Addison, who had originally been the one to suggest for Cassie to go on anxiety medication in the first place, watched as the younger girl's eyes watered and her chest moved rapidly up and down.
"Derek," she said slowly, slyly motioning to Cassie. He didn't even look at her. "Derek, please, put down the scalpel."
"YOU PUT DOWN THE SCALPEL!"
"Meredith, go get the Chief," Addison ordered immediately, watching as Cassie clenched her eyes shut as tears streamed down her cheeks.
"Do not go anywhere," Derek ordered, his voice not leaving any room for compromise.
"Karev, go!"
Alex nodded, racing out of the OR and into the one next door to find Webber.
Meredith turned her head at the sound of heavy breathing, nearly gasping at the state her person was in. "Cass?"
Misinterpreting what Meredith was trying to ask, Derek snapped his head over to Cassie, completely disregarding the fact that she was clearly not okay. "Do not move an inch, Cassandra, or so help me god—"
"Derek!" Addison shouted, her glare so heated it could practically cut through metal. "Don't do this!"
"Do not touch my patient, Addison!"
Addison's concern for Cassie grew as a soft cry left the girl's lips, as she was unable to keep it in any longer. "Cass, you need to—"
"DO NOT MOVE!"
"Meredith!" Addison pleaded.
"Derek, look at me," Meredith said calmly. "You don't have to do this. Jen's gone. It's too late. You can't save her. She's gone. We can save the baby. Derek," she insisted, "look at me."
He turned to look at her, just as the Chief entered the room, taking in the scene before him.
Cassie hadn't moved an inch, just like Derek told her to, because she was scared of what might happen if she did. Her breathing continued at a rapid pace as she wrapped her arms around herself, squeezing, looking for some type of comfort.
"The baby's still in distress," Addison said. "I need to take it out."
"Wait," Derek snapped. "Just wait. The bleeding could stop. The baby could stabilize. If you do a c-section now, she'll lose too much blood, and she'll die."
"She is dead, Derek."
"Please just wait—"
"Most of her brain is gone. For all intents and purposes, she's dead." He said nothing, prompting her to turn to Alex "Karev, page Dr. Freedman's team. Tell them we have a preemie on the way."
A second later, Addison put the scalpel to Jen's skin.
"Stop cutting! Why are you cutting?!" Derek shouted, before lowering his voice as he continued to cut out the patient's frontal lobe. "Meredith, get some more blood. She needs more blood. Get some more blood. We need more blood."
Webber stepped forward, his arms crossed over his chest as he spoke calmly.
"No more blood, Derek. No more blood." He looked from Addison, to Meredith, and finally to Cassie, frowning in worry at the resident who had never been anything but calm in an OR. "Grey—"
Meredith cut him off with a knowing nod, walking around Derek and putting an arm around a hyperventilating Cassie.
"Cass," she whispered hesitantly, never having seen her this panicked before. "Deep breaths, okay? You're okay. Come with me. You're okay."
☆
An hour or so later, Cassie was standing on the landing strip outside of the Chief's office with Meredith, simply staring at Derek from afar as he leaned over the ledge.
Her eyes were puffy, but dry, after Meredith helped her calm down using the 54321 grounding technique; five things you can see, four things you can touch, three things you can hear, two things you can smell, and one thing you can taste.
Cassie taught Meredith that not long after she moved into her house, just on the off chance that she needed it. Now, they were both grateful she did.
"You can talk to him, you know," Meredith whispered, furrowing her brows. "He's calmed down, he won't yell."
"No, I—" Cassie sighed, biting her lip as she moved her gaze down to her feet. "I don't want to. Not for a while, at least."
Completely oblivious to everything that had happened that day, Mark approached Cassie with a smile, squeezing her arm as he passed by and motioned for her to follow him.
"Let's do this," Mark whispered, making his way over to Derek and naturally assuming his girlfriend was following behind.
Cassie shared a worried glance with Meredith as she rushed after Mark, trying and failing to get his attention without speaking, since she didn't want Derek to hear.
The second Mark opened his mouth, Cassie stopped in her tracks, her eyes going wide.
"Cassie and I are in a relationship."
At first, Derek didn't move a muscle. Slowly, he turned his head, making direct eye contact with Mark. His face remained blank.
"Mark!" Cassie shook her head. "No, please don't—"
"We're in love," he continued, genuinely not hearing what she said. "I'm happy, and she's happy, which at the end of the day, is the most important thing."
Derek didn't say a word, moving to stand up straight and angle himself in front of Mark. Cassie felt her stomach drop at the dark look in his eye, figuring out what was going to happen only a fraction of a second before it did.
Derek leaned back, before throwing a hard punch right to the center of Mark's cheek.
Mark kept his head to the side for a moment, mostly out of shock. "Okay, that's... maybe I deserved that."
He paused, glancing to Cassie and seeing the devastated expression on her face, before turning back to Derek with a scowl.
"Mark, please don't—"
"No," he said loudly, not listening to Cassie as he stepped forward. "You know what? I didn't deserve that. You have absolutely no right to tell me who I can love—"
He was cut of with another hit to the face, this one causing blood to come from his nose. Cassie gasped, a hand slapping over her mouth.
And then, Mark punched him back.
Derek fell to the floor, clutching his jaw. Mark turned around, shaking out his hand as he winced. It only took a second for Derek to get up, tackling Mark to the ground. Cassie watched fearfully as Derek landed hit after hit to Mark's face, pinning him down while he didn't fight back. Eventually, Mark threw him off, starting a full blown fist fight that gained the attention of many people nearby.
Cassie stood in the middlle of the landing, only a few feet from where they were fighting. She noticed Owen, Lily, and George rushing towards them, sending them pleading looks to help.
"Do something!" Webber and Bailey did the same, impatiently pushing through the crowd. "Mark!" Cassie shouted, taking a step forward, only to be pulled back by Lily as they moved in her direction. "Derek, stop it!"
"Hey, break it up!" Owen demanded, ripping Mark from his place over Derek as he continued to punch him. "Quit it!" The two men ignored him, hitting eachother while Owen and George tried to keep them apart.
Derek pushed Mark, causing him to tumble backwards and land on the floor, right next to Cassie. Owen finally got a grip on Derek, leading Cassie to believe it was safe to check on her boyfriend.
"Mark?" Cassie frowned, her eyes burning with unshed tears as she crouched down beside him and ran a hand through his hair. "Babe, are you okay?"
In a blind rage, Derek fought Owen off, winding his arm back to deck Mark once again.
Mark nodded, a hand on his bleeding forehead as he winced. "Yeah, I'm—"
In the blink of an eye, Derek's fist collided with a nose, the harsh snap of the bone loud and clear to everyone in the vicinity.
Unfortunately for him, the nose didn't belong to the person he was aiming for.
Cassie landed on the ground with only an elbow to break her fall, her blood splattering across the tile floor.
Derek froze in place, his gaze rapidly moving between his bloodied hand and his sister, who was slowly turning her head to face him. "Cass, I—"
"Get out of here," Mark snapped, trying to help Cassie sit up straight, but being pushed away by her hands swatting at him to stop. Derek didn't move, and neither did anyone else, causing Mark to fix him with a dark glare. "I said, get the hell out of here!"
Meredith steadily walked towards Derek, as Lily and George did the same with Cassie and Mark. "Go," she whispered sternly, pushing Derek away as she turned to George with a brow raised. "You have her?"
George nodded determinately. "I have her."
Lily looked between her fiancé and his best friend. "I'll grab an ice pack," she said, sending a concerned look to Cassie as she left.
Derek shook his head, refusing to leave his sister like that. "No, I-I didn't mean to, Meredith, just let me—"
Derek made a move towards Cassie, only to see her flinch backwards as she cupped her nose in her hands.
Cassie stared up at him, tears falling due to the impact of his punch. "Don't touch me," she whispered fearfully, turning her head towards Mark without looking away. "Please don't let him touch me."
Mark stared fixedly at Cassie for a moment, turning his gaze to Derek with a deathly calm expression.
"I won't."