[Crossover] Cosette's Mobius Strip

Night brought the nightmare. Cosette pressed her bloodstained right hand against the mirror. Crying, she whispered to it, "I've killed so many people." The girl in the mirror reached out with her left hand and pressed it against hers. Warm blood twisted and wound its way down the mirror. On the increasingly clear face was a merciful smile. "No, you've always killed the same person. Shh, don't speak. Look, your skin has already been cut open. Your veins have been slashed. Your organs have been taken out. Your heart..." Ah, you've died again. When will this endless nightmare finally end? Maybe... when Cosette goes mad. A few notes before reading 1. The story mainly focuses on Sherlock and John. Other worlds are just cameos, and the plot doesn't follow the original. Please forgive any out-of-character moments. 2. If you spot any bugs, please point them out gently. The author's intelligence is limited, but I'll do my best to fix them. 3. Updates are irregular, with new chapters dropping at random. We're all respectable people here, so come ask me out! ( # ▽ # ) ↓