Because you like Sutter Keely in The Spectacular Now

John Watson is haunted by his past (who isn't) but he's starting to branch out with some help from a world class detective. See them in Sherlock.

Finn is the world's last human who's "all about" understanding right and wrong. See them in Adventure Time.

A benevolent madman with a blue box, The Doctor is traveling through time and space to heal the wounds of the universe. See them in Doctor Who.

Brilliant, violent, and only a little insane, the Joker doesn't listen to anyone except the voices in his head. See them in DC Extended Universe.

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