Ciel Phantomhive is a considerate and conservative peer to kids at his school. He's Always complimenting everyone and flashing sweet smiles so pure, you'd think he was an adorable little angel with white teeth and blue tinted locks.
Although, what most don't know, is that Ciel is not a pure little angel. Nothing of the sorts. He wasn't even a sweet boy in general until he met someone special. And once he saw that someone, he knew--just knew--that they were meant for each other. The way they smiled, skipped around, always talking to friends... he just knew that that someone would be much happier if all of those "friends" he talked to so often, even the ones that dared to be rude, were all gone.
Ciel's someone was Alois Trancy, and Ciel didn't want him to belong to anyone. Because he already belonged to Ciel in a way that no one, not even Alois, could ever understand.