Because you like The Terminator in The Terminator
Donkey Kong is a strong, banana-loving, and caring uncle to Diddy Kong. See them in Donkey Kong.
It's hard enough fighting a war. But it's worse for Commander Shepard, knowing no matter how hard you try, you can't save them all. See them in Mass Effect.
Ash Williams is a houseware clerk at S-Mart and the Chosen One. See them in The Evil Dead.
Unaware of the fact that he's a toy and made of plastic, Buzz Lightyear is a spaceman on a mission fully of snappy catch phrases. See them in Toy Story.
Marty McFly is a skateboarder, aspiring rock star, and reluctant time-traveler. See them in Back to the Future.
For Sly Cooper, stealing isn't just about the haul. It's also about the journey. See them in Sly Cooper.
Meat Boy tenaciously throws himself into danger, and when he fails, he immediately gets back up and tries again. See them in Super Meat Boy.
Raphael is a short-fused hothead who loves a good fight and some tasty pizza. See them in Teenage Mutant Ninja Turtles.