Because you like Artie Abrams in Glee
Artemis Fowl understands the way of the world. If he wins, he's a prodigy. If he loses, then he's crazy. That is how history is written. See them in Artemis Fowl.
A vain and arrogant womanizer, Roy Mustang has hidden depths. See them in Fullmetal Alchemist.
If Lisbeth Salander can hurt a bastard who deserves it by digging up stuff about him, she feels good. See them in The Girl with the Dragon Tattoo.
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.
A powerful mob boss, Vito Corleone is always making offers people can't refuse. See them in The Godfather.
Aragorn is the one true king, a title he is too humble to accept. See them in The Lord of the Rings.
Bart Simpson is an aspiring juvenile delinquent who doesn't want you to have a cow, man! See them in The Simpsons.
His murderous megalomania aside, Loki is quite charming. Just don't mention his strapping older brother; he's a tad jealous. See them in Marvel Cinematic Universe.
Steve Rogers is a good soldier. But above all, he's a good man. See them in Marvel Cinematic Universe.
The irrepressible Lucy Ricardo has never met a challenge she couldn't scheme her way into or out of. See them in I Love Lucy.