Because you like Mina Murray in Dracula
Saul Goodman can get just about any lying crook off the hook in court. Well, as long as he can make a buck out of it. See them in Breaking Bad.
Kyoya Ootori is possibly the only person who could reasonably go from VP of a school club to ruling the world. See them in Ouran High School Host Club.
Aang is already a master airbender and once he learns to manipulate water, earth, and fire, he'll be truly unbeatable. See them in Avatar: The Last Airbender.
With the loyalty and pluckiness of a puppy, Nana Komatsu is a hopeless romantic. See them in Nana.
An aloof punk rock goddess, Nana Osaki has a surprisingly big heart. See them in Nana.
Dominic Toretto lives his life "a quarter mile at a time", and he burns through those miles faster than anyone. See them in The Fast and the Furious.
One of seven supernatural babies who was born to a mother who was never pregnant, Ben Hargreeves is trying to save the world from an apocalypse in 8 days. See them in The Umbrella Academy.
Mikasa Ackerman is a near-perfect soldier who won't break her stone-faced expression whether she's killing foes or protecting loved ones. See them in Attack on Titan.
Severus Snape is a misanthropic potions teacher with a vindictive streak. See them in Harry Potter Series.
Orphan Bruce Wayne has a tortured soul, but he's trying his best to weed out corruption. See them in DC Extended Universe.
Po is a clumsy, friendly panda who likes to take it easy. But now he's expected to save the world? See them in Kung Fu Panda.