I think Liz killed Agni or that weird orange coloured hair guy, but Liz has definitly met realCiel and is staying with him.
Maybe Liz did do it. Or maybe 'Ciel' and Liz did it together. Why would Liz write that message? Unless the message has a meaning I'm missing
Which makes it likely he is realCiel.
Back to the other chapters I think lol.
What he meant by "Who stole the candy in my tummy" was a reference of the chapter when Sebastian was summoned and asked FakeCiel if he would like to take the "thing". The background at that panel shows a child's body destroyed. AKA RealCiels body. Thus taking the Phantomhive ring officially making FakeCiel the successor. Making the candy a reference to the ring that was taken.
Oh and that was really RealCiel killing Agni. I can discuss further more but Im lazy and I think you dont want to read anymore of it.
What Chapter was the summoning again?
real!Ciel had someone else with him. There were two people in that scene: Ciel was the one with the gun who shot Soma and the other person had the knives. It wasn't Lizzie who attacked: she has no reason to kill Agni or Soma and even if it was for Ciel, I don't think she'd kill someone else without good reason. And as you said, Agni could nearly match Sebastian, so Lizzie wouldn't be able to kill Agni so easily. I'm betting whoever killed Agni is another supernatural being (hopefully a demon: they used knives like Sebastian does :) ).
How about if you say... A reapers soul?
That makes no sense. How can he kill Agni. He was one of the most powerful characters, HE EQUALED SEBASTIAN! How can a 13 yr old kill him with a tiny knife? and the candy message dosen't really make sense. Also, this series is probably going to end with Ciel killing 'Ciel' and then Sebastian taking Ciel's soul. 'Ciel' is probably one of Undertaker's Dolls.