Because you like Mrs. Krabappel in The Simpsons

L is enigmatic, child-like, and one of the smartest people in the world. See them in Death Note.

Light Yagami has a plan to make a better world, and morals won't stop him. See them in Death Note.

The adventurous daughter of Port Royal's governor, Elizabeth Swann would rather conspire with pirates than sit pretty in her corset. See them in Pirates of the Caribbean: the Curse of the Black Pearl.

Smart, sarcastic, and loyal, Stiles Stilinski doesn't just want to be the sidekick in someone else's life. See them in Teen Wolf.

It's hard to tell if Dean Winchester cares more about saving the world or his 1967 Chevy Impala. See them in Supernatural.