Because you like Marlin in Finding Nemo
Deadpool thinks life is an endless series of train wrecks with only brief commercial-like breaks of happiness. See them in Deadpool.
Taking down villains, standing up to sexism, and pulling off a bright-red lipstick are all in a day's work for Agent Peggy Carter. See them in Marvel Cinematic Universe.
An off-beat dork, John Egbert is funny, inventive, and endlessly optimistic. See them in Homestuck.
With his perfectly combed hair and flashy military outfits, France can charm the pants off of anyone—well except his fellow nations, it seems. See them in Axis Powers Hetalia.
Burton Guster is a level-headed investigator with a "Super Sniffer" nose. See them in Psych.
Suzy Bishop is only 12, but her withering stare and withdrawn personality are enough to make anyone wilt. See them in Moonrise Kingdom.
Hiro is a free-spirit and remarkable genius who loves bot fighting and problem-solving. See them in Big Hero 6.
Scooby-Doo always keeps his priorities in order: eat snacks first, solve mysteries later. See them in Scooby-Doo.
She's mostly doom and gloom, but you'd get nowhere without Sadness. See them in Inside Out.
Yuri is living in the afterlife, which takes the form of a high school where no one dies. But if you follow the school's rules and live a "normal" life you vanish. See them in Angel Beats!.
Nomi Marks is a brilliant hacker with an open-minded, accepting spirit. See them in Sense8.