Because you like Mikey Waters in My Own Private Idaho
She's mostly doom and gloom, but you'd get nowhere without Sadness. See them in Inside Out.
Nothing instills more fear in the Empire than the deep kshhh of Darth Vader breathing through his helmet. See them in Star Wars Series.
Damon Salvatore used to miss being human. Now he can't think of anything more miserable. See them in The Vampire Diaries.
Belle has ready every storybook in town, and she's slowly realizing that life is no fairytale. See them in Beauty and the Beast.
Severus Snape is a misanthropic potions teacher with a vindictive streak. See them in Harry Potter Series.