Because you like Clare Abshire in The Time Traveler's Wife
Helena is a mentally unstable, childish, and completely merciless. And most of all, she's an unstoppable killer. See them in Orphan Black.
Her unhappy childhood has left her unsure of the existence of happy endings. Mary Jane Watson hides her pain beneath a joke and a smile. See them in Marvel Cinematic Universe.
Remy could be a five star Michelin chef, the only problem is that he is quite literally a rat. See them in Ratatouille.
Bob Belcher runs a lonely burger joint, and even though his wit is lost on his eccentric family, he doesn't let that faze him. See them in Bob's Burgers.
Holden Caulfield is convinced that the whole adult world is full of phonies. See them in The Catcher in the Rye.
The Little Prince is a childlike wonder personified in a tiny package. See them in The Little Prince.
It turns out the girl of your dreams just might have dreams of her own. See them in (500) Days of Summer.
Spencer Reid's super-smarts helps catch killers, and his social awkwardness endears co-workers. See them in Criminal Minds.
Rose Hathaway is a reckless, rebellious smartass who's training to be a royal vampire guardian. See them in Vampire Academy.
Chaos is what killed the dinosaurs, and there's nothing Jason "J.D." Dean loves more than chaos. See them in Heathers.
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.