Because you like Rudy Ruettiger in Rudy
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.
His elfin self-confidence can border on pretension, but Legolas Greenleaf is a fearsome fighter and a loyal friend. See them in The Lord of the Rings.
Brilliant, violent, and only a little insane, the Joker doesn't listen to anyone except the voices in his head. See them in DC Extended Universe.
With great power comes great responsibility, but Peter Parker always seems to get the short end of that bargain. See them in Marvel Cinematic Universe.
Castiel might be an immortal angel, but the human world is still more than a little confusing. See them in Supernatural.
A dreamy space cadet, Luna Lovegood has never met a conspiracy theory she didn't believe in. See them in Harry Potter Series.
An escaped convict on a mission, Sirius Black is brooding, brave, and reckless. See them in Harry Potter Series.
His murderous megalomania aside, Loki is quite charming. Just don't mention his strapping older brother; he's a tad jealous. See them in Marvel Cinematic Universe.
A bookish know-it-all with a bossy streak, Hermione Granger always stands up for what she believes in. See them in Harry Potter Series.