Because you like Roxanne Simpson in Ghost Rider
Poison Ivy is a seductive, venomous botanist laments the fact that there are so many people to kill, yet so little time. See them in DC Extended Universe.
Jacob Black is the boy next door who's also the wolf next door. See them in Twilight.
Bella Swan thinks of it as her job to help her parents and protect her friends, even though it often ends up the other way around. See them in Twilight.
A 100-plus-year-old who looks like a dreamy teenager, Edward Cullen warns girls to avoid him, which makes them want him even more. See them in Twilight.
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.
When the going gets tough, Rick Grimes gets tougher. It's a very useful trait when the world goes to hell. See them in The Walking Dead.
Homer Simpson is a beer-loving disaster in charge of nuclear safety in Springfield. Everybody run! See them in The Simpsons.
Charming and confident, Gus Waters is determined to leave a lasting mark on the world. See them in The Fault in Our Stars.
Indiana Jones is a swashbuckling archeologist who hates snakes, Nazis, and priceless artifacts falling into the wrong hands. See them in Raiders of the Lost Ark.