Because you like Arthur in Merlin
Walter White's knowledge of chemistry allows him to cook astoundingly pure meth, leading to a rapid – albeit tumultuous – rise in the criminal drug world. See them in Breaking Bad.
Don't ask the ruthless queen of the Tokyo underworld any questions unless you're fine with losing a limb. See them in Kill Bill vol. 1.
Trying to get through school without being a burden to anyone, Tohru Honda stays cheerful despite her difficulties. See them in Fruits Basket.
Betty Cooper seems like a sweet girl, but she also has a dark side and can go beyond what's safe or sane. See them in Archie Comics.
Ramona Flowers is a delivery girl who's been through her fair share of bad breakups. Super-bad breakups! See them in Scott Pilgrim vs. the World.
Hotheaded and arrogant, Kaneda is nevertheless fiercely protective of the biker gang he leads. See them in Akira.