Trigger warnings, fair readers. If you can't handle self-harm, I suggest you wait for the next chapter.
*~*
"Sherlock," a deep voice crooned. The young man in question flicked his eyes open and darted them around John's room. Since they'd returned from Jim's drug den, John had generously given Sherlock his bed to recover on whilst he slept on the lounge downstairs. Sherlock's eyes landed on a dark figure next to the doorway. It crept over to the bed and traced delicate fingers across Sherlock's face, grabbing onto his jaw softly and tugging him from the sheets. Sherlock's body obeyed the silent command and he was led into John's bathroom. The figure stroked across Sherlock's arm and linked its fingers with his, leading them up to the light and turning it on. Sherlock jumped when he only saw his reflection, but that in itself was frightening. He noted how dreadfully thin he was, and his eyes looked hollow, surrounded by large, dark circles that almost led down to his prominent cheekbones. He jumped again when he felt the ghosting, hallucinated hands push his own towards the sink and closer to the mirror. Sherlock whimpered at his reflection. His skin wasn't the pale porcelain that he usually donned due to an anti-social life, it was...grey.
He looked like he was dead.
And it disgusted him.
"Sherrrrlooock," teased the hallucination, whispering gently into Sherlock's thoughts, "we're going to open the drawer, alright?"
"No," Sherlock breathed, "you can't make me."
"I can," it whispered again, manipulating Sherlock's hands until they gripped the bathroom drawer, sliding it open to reveal the assortment of items within. The hallucination pushed Sherlock's hand inside and grabbed a fresh razor from the back of the drawer, popping the plastic covering off with his thumb. He snapped the plastic binding of the razor and stared in fear at the metal rectangles before him.
"Stop, please," Sherlock whimpered, breathless, "why are you doing this?"
"Because I hate you," rumbled the hallucination in a voice Sherlock recognised as his own, "I hate you and I want you to suffer."
Their linked hands grabbed at the small blade and brought it up to Sherlock's wrist. The first cut brought tears to Sherlock's eyes as the pain shot through his body. The hallucination tightened its grip around Sherlock's hand.
"I hate you," it hissed, making a deeper cut into Sherlock's wrist, "I want to hear you say it."
"No," Sherlock murmured, tears mixing with the blood on his forearm. The hallucination growled and slashed the blade across Sherlock's palm, making him hiss with pain.
"I hate you. Say it."
"I...I..." he stammered. The blade was brought across his palm again, "I hate you."
His head was forced up, making him stare at the swollen, dead reflection that stared back at him in digust.
"Again," the hallucination commanded.
"I hate you," he seethed at his reflection, the blade swiping across his wrist again, dripping blood on the tiles below.
"Again."
"I hate you."

Cut.
"I hate you."
Cut.
"I."
Cut.
"Hate."
Cut.
"YOU."
The blade dropped from his hands as the door to John's room opened. The hallucination freed him with a disgusted glare and Sherlock dropped to the floor, lying in the small pool of blood that had fallen from his forearm. John's footsteps trudged hesitantly into the room, stopping at the bed before turning towards the light of the bathroom. Through his pained haze, Sherlock heard John's gasp as he entered the blood-soaked bathroom.
"Sherlock! What the hell? Why did you do this?" He cried. John's parents rushed into his bedroom, suddenly staring wide-eyed at the teenager lying on the bathroom floor.
"Sherlock," John's mother breathed. Sherlock whimpered and shuddered as the last tear fell from his eye and onto the floor.
"I hate Sherlock."
*~*