Because you like Kathy in Never Let Me Go

A suave demon, Crowley grants humans their wishes in exchange for their soul, only to find loopholes that benefit him. See them in Supernatural.

Don't mess with Mickey Milkovich unless you want to see the wrong side of one of his many guns. See them in Shameless.

Kyoya Ootori is possibly the only person who could reasonably go from VP of a school club to ruling the world. See them in Ouran High School Host Club.