Because you like Lieutenant Worf in Star Trek: The Next Generation

When the Sorting Hat touched Draco Malfoy's head, it placed him in Slytherin, a house that has turned out more dark wizards than any other. See them in Harry Potter Series.

People think that because Tris is small, or a girl, or a Stiff, she can't possibly be cruel. But they're wrong. See them in Divergent.

Regina Mills is a cold evil queen turned chilly town mayor. See them in Once Upon a Time.

Kat Stratford is part of the "out" crowd and proud of it. See them in 10 Things I Hate About You.

Damon Salvatore used to miss being human. Now he can't think of anything more miserable. See them in The Vampire Diaries.