Dancing upon the Twisted Mirrors

{A Xiao x Twisted Wonderland crossover}
{Will contain dark themes, gore/body horror in italicized paragraphs unless explicitly said otherwise}
{Will make most if not all the gore/body horror able to be skipped without it affecting the story too much, the gore/body horror will be in Xiao's past memories}
{Can be read as x reader, I don't mind it}

He knows he's dead, yet why is he still able to feel the ache in his lungs when he breathes? Why is he able to feel wood beneath his fingertips when he touches the surrounding walls?