Secrets of the Knighttime {Black Butler/Kuroshitsuji Fanfic}

Sebastian is frustrated when a taunting girl with strange feline tendencies offers him her soul for free. Is she oblivious to the consequences or truly tired of living and wishes for it to end? Sado-masochistic owner of an insane mind, Zylphia is an odd mix of childish, mature, kind and dangerous, longing for a death only demons can grant and holding a strange burning hatred for Reapers. There's nothing to be done but to play a game for the soul, and what a tedious, troublesome and intriguing game it will turn out to be, as Sebastian soon finds out.