"I'm just a butler."
"As the butler of the Phantomhive family, how can I do it without this ability?"
Listening to these familiar and unchangeable lines makes people happy. Maybe, just maybe, the contract does not mean loyalty, and betrayal is possible at any time.
I have long forgotten how to laugh happily. Revenge is just an introduction and an excuse! Without hate, I don't know what else would justify my existence.
"Sebastian, I order you to eat my soul after the contract is completed!"
"Yes, my lord."