The man behind the mask: Sherlock X Reader

"Well just try to make it casual, not too serious." She said.

"How? Like-oh yeah Sherlock, so you know we're in a relationship? Well yeah surprise, I'm your enemy's sister."

"Your Moriarty's sister?" I heard a voice ask, from behind me making me spin towards him.

"Oh shit"

-X-

"I'll call you back" I said, quickly hanging up to face Sherlock.

"Sister." He mumbled.

"Sherlock?" I asked, confused as to why he was mumbling that one word.

"I knew you had a brother, I didn't know it was him" He muttered, making me sigh.

"Sherlock..." I sighed.

"Are you working for him?!" Sherlock demanded, making me jump and take a step back before violently shaking my head.

"I'm not, I swear! I haven't seen him since he left!" I said, pressing my back against the wall.

"I have to go" Sherlock whispered, before turning to leave.

-X-

"Y/N, you okay?" John asked as I exited Sherlocks room, he was, of course, long gone.

"Yeah, why?" I asked, grabbing my jacket from the table.

"You look sad" He shrugged, he obviously didn't hear our conversation.

"I'm just tired, it's been a long day" I smiled, before saying goodbye and heading to leave.

-X-

"Hey, Y/N. What are you doing here?" Greg asked, as I walked into Scotland Yard.

"I need something to do, keep me busy" I shrugged, standing next to him.

"Well, we're on a case b- "

"I'm helping" I said, laughing after I finished my sentence.

"Follow me" Greg chuckled, leading me into a room where all the evidence was pinned up on a board.

"So, murder?" I asked, walking up to the board and began looking over the evidence.

"Yeah, a 28-year-old man was found dead in his flat."

"Who are the suspects?" I asked, running my finger along the suspects.

"Daniel Cooper, the victim's brother. He claims he was working that night." Greg informed.

"Claims?" I asked, confused as to why he said claims.

"He is one of the suspects." Greg said.

"You mean, he is one of the main suspects" I deduced, to which Lestrade nodded.

"Y/N, what are you doing here?" Anderson asked as he walked into the room. Rolling my eyes, I continued to look over the evidence.

"Who else?" I asked, spotting Anderson and Lestrade talking out of the corner of my eye.

"His girlfriend, she said she was at her mums" Lestrade announced.

"See, you said she said." I stated, looking over the crime scene photos.

"Well, yeah- "

"So, she isn't one of the main suspects. That's a shame, I thought Scotland Yard was good" I sighed, turning to face Anderson and Lestrade who held confused looks.

"The brother and the girlfriend were having an affair. The girlfriend got pregnant, she assumed it was Daniels and didn't know how to tell her boyfriend. She had to tell him, because he would know due to the fact they hadn't had sex in months with his busy working schedule. She told him, he got slightly mad and started to leave, she grabbed a glass, hit him over the head which knocked him unconscious. He stopped breathing for a while, she thought he was dead so she strangled him with some rope and then left to go to her mothers." I concluded, leaving Lestrade and Anderson is awe.