Because you like Johnny Storm in Fantastic Four
It's easy to see why Poe Dameron would side with the rebellion: he's bad at taking orders, likes to show off, and is committed to the cause. See them in Star Wars Series.
After years of living vicariously through other people's heroic stories, Wade Watts is about to become a hero himself. See them in Ready Player One.
A determined and cold-hearted spy, Cassian Andor will do what it takes to stand up to the evil Galatic Empire. See them in Rogue One.
Bucky Barnes used to be a good-hearted American soldier. Now he's the cold-hearted Winter Soldier. See them in Marvel Cinematic Universe.
K-2SO is a blunt and sarcastic reprogrammed Imperial droid who is always up for an adventure. See them in Rogue One.
Oscar Martinez is a national accountant in an office of weirdos. See them in The Office.
They say prison changes you, and Piper Chapman is figuring that out the hard way. See them in Orange Is The New Black.
Howard Wolowitz is an engineer whose serious mommy issues somehow haven't dimmed his confidence. See them in The Big Bang Theory.
King Schultz is about as color-blind as a man of his era can be. See them in Django Unchained.
Kesuke Miyagi is a karate expert who thinks the best way a scrawny high schooler can learn how to defend himself is by washing every surface in sight. See them in The Karate Kid.