Columbo always reminds me of being a nine in a non-stereotypical way.
He is always calm, always underestimated, he puts people at ease until he starts cracking the case. A prime example of an intellectual nine, imo.
Usually he's calm, happy, and works to promote peace. Other characters are quick to rise to anger, but he isn't one for taking life too seriously. He's a natural optimist and spreads hope and unity.
However, he also suppresses his negative emotions beyond healthy limits - especially anger. After he lost his beloved bison, Appa, he went ballistic and entered into the Avatar State, endangering everyone around him with his rage. After the episode, it's obvious that he bottled everything up for too long, and just needed a catalyst to set him off.
Bruce Banner, possibly?? Film-verse, I have absolutely no idea comic-verse for I have never read them and the cartoons show the Hulk more than Banner. On the surface, keeps calm no matter what, and he suppresses his anger very well, but when it gets let out hello green rage monster. Does best to avoid conflict.