Revenge doesn't solve anything (Ciel X Reader X Sebastian)

It was crazy how fast you saw a change in him. Ciel, you and Lizzy knew each other for years when you were little, but after the incident, you never saw Ciel smile ever again. It wasn't just that, but Ciel's devilishly handsome butler, Sebastian, was strange in a way. You just got this bad vibe from him. Well, this will be interesting....