A flashing blue and yellow eye
"Try this" Gaster said as he helped you perfectioning the time machine in your lab, handing you instruments.
Two whole months had passed since you and Gaster became a thing, and ever since then he helped you when he could with your project, something you really appreciated.
His subordinates now had gotten used to his more and more absent presence at his lab: when Gaster wasn't there, they knew that he was with you. But at least, they were happy for both of you.
Overall everyone was happy for you: Toriel had even thrown a party at her house to celebrate the new couple, and you can actually say you had fun.
Well, except for one person.
Jayden often texted you some days to invite you out, and sometimes he even said things like "I love you". Everytime he would text you messages like these, you would show these to Gaster, he would glance at them slightly disgusted and he would erase the distance between you two by kissing you, and passionately, reminding that you were his girlfriend.
And now there you were, adjusting the time machine, with him by your side, lending you tools to prepare codes and arrange mechanisms.
However, the more you worked, the more you grew doubtful about one thing, and your face clearly didn't hide your inner thoughts, as Gaster immediately noticed that something was going on.
"Y/N, are you okay?"
You blocked yourself when you heard his words, partly softened by his question: it meant he cared, and you found yourself safe in his tenderness.
"Yeah, I'm okay. It's just...I'm having doubts about this time machine" you said in the end.
"What kind of doubts? You don't want to construct it anymore?"
"No...well, I don't really know at this point. I mean, do I really want to bring back Lauren, or am I just too much dedicated to this project to abandon it now? How would my life be if I didn't kill her? Would we still be best friends? Am I feeling obliged by the sense of guilt I felt before? I don't know what I feel" you said before you could hiss in pain as you got yourself hurt with an instrument, and got yourself a cut on your hand.
"Damn it" you said in pain.
"Wait, come here, there's medical equipment over there" he said, grabbing your other hand and conducting you to a table nearby, where there was a small white suitcase with a red cross in the center.
He made you sit down on the table and he opened the suitcase, picking up disinfectant and bandaids.
"Here, let me have a look" he said, professional as ever.
You showed your hand and he examined it, carefully touching the area where you were not hurt to understand how deep was your cut.
"You're lucky, you could have gotten a worse cut than this" he said as he picked a piece of medical cotton and moistened it with disinfectant, putting it right after on your cut gently.
You hissed in pain again, catching his worried glance. How cute, he was afraid for you. You smiled for him, to reassure him that everything was okay, and he immediately got relieved after seeing your smile.
"Thank you dear" you said as he put the bandaid on your hand and gently rubbed it right after.
He smiled and looked at you tenderly as he rubbed your hand delicately.
"So, about what we were talking about..." he started talking as he looked at your hands and continued caressing them.
You slightly gasped after remembering what you were talking about before you got hurt: bringing back Lauren.
"If I may ask Y/N...how do you feel? Are you happy right now with your life?" he asked.
"What kind of question is that? Of course I'm happy, I have you" you said with a straight face, which caused his cheeks to faintly tint with a lavender colour.
"I'm...relieved I can bring happiness to you" he said, playing with his fingers now as he was being shy "I've asked you this because, well, I needed to acknowledge if you were happy with or without her. Do you miss her?"
"Yeah, I do, but for a while recently I've started thinking that I could do nothing about what had happened: I killed her inadvertedly, and I suppose that is fate...but this project has been going on for five years, I can't abandon it now, can I?" you said
He then smiled to reassure you and cupped your cheeks in his hands.
"Hear me out then: we will continue the time machine, and if you want to bring back Lauren we will use it for this cause, but if you don't feel good about it, we can simply use it for something else: I won't let five years of your life be spent in waste"
Gosh I fall in love with him more everyday, you thought, not believing that you were finally happy in a relationship.
"Thank you love, it means a lot" you said as you put your hands on his, as they were still on your cheeks, and caressed them.
He smiled as he caressed you as well, and his cheeks started growing purple. Was something going on in his mind?
"You...make me a lot happier too" he said, looking away and making you awe at his cuteness.
You giggled and he couldn't take it anymore.
"Damn you, come here" he said as he pulled and embraced you in his hug as you kept giggling, and then you encircled his neck with you arms, as he started kissing you on your cheek repeatedly.
But, after a minute of smooching and kissing, an alarm ringed in your secret lab: an alarm that signaled if someone was knocking on the door of your office upstairs.
You and Gaster both looked at each other in amazement and curiosity: who could it have been?
"Wait for me here, I'll be right back" you said as you kissed Gaster on the lips and obtained a smile from him.
You ran up the stairs and, after you peeked outside of the secret door, ensuring that no one had actually entered in your office without you allowing, you came out and opened the office door.
Jayden.
"Jayden? What are you doing here?" you asked, honestly surprised. You had always told him no, that you didn't want a relationship with him. Why was he there in that moment?
You felt a cold chill run down your spine.
He looked hopeful into your eyes.
"Y-Y/N! Alas, I meet you at last!" he said with a nervous smile, playing with his fingers
"...Jayden? Why are you here? I don't remember you being scheduled for an appointment"
"Y-yeah well, I...sneaked in here"
"You WHAT?!" you asked shocked, feeling the urge to go back downstairs to your beloved skeleton who was waiting for you.
"Listen, I had to do it! You weren't giving me a chance, and...just please, why won't you give me a chance?! I promise I will make you happy forever!" he asked with a pleading look, crossing his fingers as if he was praying.
"Jayden, I've already said no. Plus, I am now engaged, so I can't make you happy. Don't make me do things you would regret, and you'll have a bad time" you said with a menacing look, now getting bothered by his presence.
He looked at you, as if something had awakened in him, and his nervous attitude now changed into a...scary composed one. Wanna know why it was scary? His shaking fingers ready to strangle you were the only thing of his body moving.
"Y/N, this is what you asked for"
Predicting what he was about to do, you dodged his arms that were just about to grab your neck, and as you quickly squatted to dodge him you hit him under his belt, causing him to kneel down in pain.
Your blood was cold in your veins.
Gaster, I need to get to Gaster immediately! you thought, your boyfriend being the only thing in your mind.
You quickly pulled the book-lever, followed by Jayden's murderous look, and went downstairs, reaching your beloved.
His smile vanished when he saw the scared look in your eyes, and he immediately ran towards you to hold you in his arms.
He hugged you as you caught your breath, but there was no time at all, you had to escape!
"Y/N, what is happening?!" he asked you, terribly afraid.
"There's no time, quick, teleport us away from here!"
But it was too late. Jayden had reached you two, and your heart stopped beating when you heard his steps behind you. As if sensing your feelings, Gaster held you tighter.
"So that bitch is the reason you want us to teleport" he told you as he looked into Jayden's eyes, filled with killing intents.
You held onto his chest, refusing to let go.
That's when you felt a light pat on your shoulder, and felt Gaster letting you go.
"Gaster...?"
"You know Y/N, I've actually gotten tired of all this situation where my girlfriend is continually harassed by someone like him. So let me just give him a lesson, for you my dear" he said as he covered you, approaching Jayden.
The two men looked at each other as if they were ready to kill each other, and as Gaster closed his hand in a fist, he punched Jayden right under his chin, but, as Jayden fell on the floor, he grabbed Gaster's legs, making him fall as well.
"Gaster!" you screamed, suddenly feeling unable to move when you saw his skull hit the ground and him being held tightly onto the ground.
He quickly glanced at you, as if to ensure that you were right, and smiled.
That's when he mouthed something.
"Cover your ears"
He suddenly snapped his fingers, and a weird, deer-like creature appeared in the air, right on top of both Gaster and Jayden. You couldn't see it well as Gaster ensured that the creature didn't face the time machine. Why though?
"Jayden, I'm sure you've heard of this" he said "after all, this is my most popular creation"
Jayden looked horrified at the creature, and well, you actually enjoyed that terrified look in his face.
"I hope you won't mind it being the cause of your death" he said.
As you saw that he was about to snap his fingers again, you remembered what he told you before, to cover your ears, and you did so. After noticing that you had done so, he smirked and finally snapped his fingers.
As he snapped them, the skully creature opened its mouth and caused an explosion to roar from its mouth, as you now understood why it didn't face the time machine: Gaster didn't want to destroy your hard work.
You closed your eyes after seeing all white for a second, but when you reopened them, a horrifying sight popped up.
Jayden had dodged the blast, and he had a syringe in his hand. A syringe that was partly in Gaster's arm, as he blocked Jayden's hand with his other arm, preventing him to put the syringe any further and inject the liquid in it.
You didn't have any idea about what that was, but judging from Gaster's expression, it must have been painful.
You were paralysed in fear.
But, suddenly, you felt something run in your veins. You felt a familiar sensation in your body, enveloping you as a cold blanket. A sensation you felt when you killed three people some years before.
Adrenaline.
It's time to stop. It's just like a few years ago, but this time, I have to protect for real someone I care about.
You directed towards your purse, under Gaster's painful look. He had written "what are you doing? run away!" all over his face.
He screamed in pain as Jayden managed to inject the syringe a little bit further.
"Doctor Gaster, I'm sure you know that this liquid can also kill you if too much of it is injected, don't you?" Jayden said, completely not giving attention to your sudden movements.
"What are you trying to do, Jayden?! Do you think that by killing me you can obtain Y/N's love?!" he said, under the sound of your purse opening.
"That would be the best! But if I cannot, then at least I would show her what I would do to whoever approaches her!" Jayden yelled
A sound of a trigger filled the room.
"You know, I don't even feel sorry for you, because Y/N will always be mine! Actually, I would feel honored if I was in your place, you are the first example for all people out there looking for her! Now die!"
Bang.
Gaster closed his eyes, waiting for the sudden pain after hearing the sudden bang. But when he opened his eyes, he saw Jayden with blood all over his throat, looking at him with a rather surprised look.
He looked up, and saw you with a gun in your hand. A gun that was exactly pointed at Jayden's neck.
You approached the two men, and kicked Jayden off, freeing Gaster from all of that weight, still pointing the gun at him.
"You know, a bullet in your throat can kill you in less than a minute, so I'll be quick" you said, as Jayden looked at you, unable to speak after losing too much blood.
You put one of your heels on his almost lifeless body as if he was nothing but a mere little rock to step on the street.
"Don't say I didn't warn ya: I've done something you would have regretted doing" you said as you put pressure into your heel on his body.
"Second of all, this is what you get for almost killing the only person I've ever loved and will only love"
You now pointed at his head
"And finally, rot and wait for me in hell, where I'll give you nightmares for eternity!" you finally yelled.
You shot another bullet, killing him definitely. You slowly put your gun down, as you looked at Gaster.
He looked at you surprised into your eyes, as if you had something on your face.
"Y/N...your eye..." he said, unable to move as he clenched on his arm, completely shocked by what you had just done.
"What's wrong with it?" you asked as if you didn't just kill a man.
"It's...flashing. Blue and yellow"
You slowly looked at your reflection on the time machine, and saw that indeed, your left eye was flashing blue and yellow.
"Oh yeah, it's flashing" you said with a straight face, as if it was normal for your eye to flicker.
Somehow, your flashing eye made you realise what you had just done, and you looked terrified at Gaster, who was looking at you.
"Oh my god, Gaster...what have I done? The worst thing is that I don't feel guilty at all" you said as you let go of the gun and reached your boyfriend.
He was quite literally unable to move.
"Gaster, how are you feeling? What was that liquid that he was trying to inject?"
Your lover looked down at his arm, where a little hole caused by the syringe's pressure could be seen.
"That was the liquid used to immobilise Monsters who threaten people"
The oddest thing is that...only Wizards own this type of weapon. Why was it in someone like Jayden's hands? he thought
He shook the thought off as he felt your gaze on him.
"Gaster...what is going to happen now? Are you going to leave me after you have seen how I really am? A murderer?" you said, looking embarassed away.
He slightly flinched as he moved nearer to you, trying to reassure you.
"Y/N, you were just trying to protect me. Why would I leave you? I would never leave you"
He flinched again as he caressed your cheek with his arm, as a tear fell down your eye.
You were crying not because you had killed a man, but because you had already predicted what would have happened and figured that he would have been left alone.
"...Y/N? Love, why are you crying?" he asked, not realising what mess was going to happen.
And you weren't ready to saying goodbye to him.
The Civil War between Humans and Monsters was about to start.