Because you like Trinity in The Matrix
Holly Golightly spends so much time trying to be other people's dream girl, she doesn't really know what kind of girl she actually is. See them in Breakfast at Tiffany's.
Severus Snape is a misanthropic potions teacher with a vindictive streak. See them in Harry Potter Series.
Belle has ready every storybook in town, and she's slowly realizing that life is no fairytale. See them in Beauty and the Beast.
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.
Jenna Rink is physically 30 but emotionally 13. She has a better excuse than most. See them in 13 Going on 30.
Christine Daae has been secretely taking lessons from a phantom musician. It sounded less creepy in her head. See them in The Phantom of the Opera.
Luke Skywalker always wanted to leave home, but he didn't expect that it would be as part of a quest to rescue a princess and save the galaxy. See them in Star Wars Series.
Some say to survive in Underland you need to be as mad as a hatter–which, luckily, he is. See them in Alice in Wonderland.
Rupert Giles is a librarian on the outside, fearless evil-fighter on the inside. See them in Buffy the Vampire Slayer.
Amber Holt is perpetually caught between forging her own path and stumbling around in the dark. See them in Parenthood.
Impassive, overly literal, and a little short on people skills, Angel dedicates her life to enforcing the rules. See them in Angel Beats!.