okay so like the other ciel probs murdered everybody lallasklmd,sijouhjbjvfad

that's what i'm slightly thinking
like something inside him got triggered, and he went crazy

because Vincent's ring goes missing, realCiel writes on the wall "who stole the candy in my tummy" (i remember reading somewhere that this "candy" is most likely the ring)

Tanaka at the end of this chapter says "Master Ciel is..." and gets stabbed

idk- i may be completely wrong