I wanted to write one fan fiction with a headcanon about Doll... then this happened...
"You'll pay! Smile!"
"…Sebastian…"
An inhuman fury enveloped the child like Hell's flames around a sinful soul. Handsome face was bruised and bleeding, hair disheveled and burned. The young Earl of Phantomhive was a charred mess. Teeth grit, creaking under his jaw as multicolored eyes seared into his most prized servant. "What have you done?"
Innocent and gentle, the demon looked up at his master, the smallest smiles upon his flawless face. "I'm not sure I understand, My Lord? Did I not fulfill your wishes properly?"
"I told you to kill her!" Ciel barked and in an instant he lashed like a rabid dog. He grabbed Sebastian's collar, shaking the fiend violently, "I gave you an order! I told you to destroy her!" The servant was expressionless, tamed hair barely moving.
"You had never instructed me to kill the girl, My Lord, I apologies for the severe misunderstanding. Would you like me to correct it?"
"I don't give a damn! You are supposed to protect me, Sebastian! Have you not witnessed what has just occurred? The child was coming at me with a knife!"
"If the girl was a threat to you my lord, I would have taken care of her."
"You fool!" Ciel cried out, tears falling from his lashes like rapid gun fire, "You follow every order! Every wish! Every command! You are my guard dog! My loyal servant! You are supposed to save me."
The demon pouted, almost looking hurt. "I am afraid you've called upon the wrong person. You seem, My Lord, I am not a savior, I am simply your tool, your bible."
The earl cried out, hitting his butler harshly against his cheek, "Don't give me that Sebastian! Especially from you!"
"My apologies-" Another slap.
"Shut up!" The boy screamed, sobs breaking his voice with every word. How dare Sebastian say such a thing? How dare he betray his master, his owner? After all that had happened, after all they had done that day. From the slaughter of the innocent, to the murder of that damned circus! How dare that disgusting pawn leave that girl to survive? "Shut up, shut up, shut up, shut up!" He shoved the demon aside, revealing Doll's unconscious form behind him. The earl snarled, crushing the girl's last candy beneath his feet. "Sebastian!" He called out, as if the servant was miles away. Shining shoes grazed Doll's soft hair. "If you do this again," he murmured, "if you refuse to listen to me, your agony will be intolerable." Ciel slipped his foot over Doll's gentle face, still stained with tears.
"Do you understand me, Sebastian?"
Behind him, the servant bowed, "Of course, My Lord."
Not another second passed before the child pressed with all his weight, snapping the girl's skull into the innocent form splattered across the grass.
Sebastian glanced up, watching the earl play in the red matter with his shoe like a child in a rain puddle. A wash of pride came over the otherwise emotionless servant. The boy had certainly grown into quite the beautifully violent young man. It had seemed that the earl and his demon had became one and the same.
"I will be with you until the end, I will never betray you, I will never harm you, Ciel Phantomhive."