Sebastian Michaelis is a demon, who is currently bonded with his master Ciel Phantomhive, they're currently at the Noel's ark circus when Ciel gives Sebastian a demand to burn down the owners mansion

Ciel:"burn it down Sebastian.." Ciel left the room, suddenly Joker comes in

Joker: "What- What are you doing-?!"

Sebastian:"Burning this building down, and nobody..will stop me, it was my masters demand"

Sebastian's red eyes glew, he then burned down the mansion,Joker passed out