Fuck it, Rush Hour headcanons in our lord's year 2026:
Lee is a repressed gay man, Carter is bisexual. Neither of them know this because they are Men in The 1990s. (see: very stupid)
In 1, Lee mentions that Juntao killed his partner. Lee's partner was a nice guy, around the same age. They didn’t know much of anything about each other outside of the work and that was ideal. It’s one of the things he regrets, because all he could say was that he was a good man and a good officer.
Captain Diel knew Carter’s father. Probably encouraged him to go to the academy because he knew that under all the bravado that he was a bright kid.
Carter keeps his father’s class ring as his memento. He never takes it out with him on the job because it’s not something he’s willing to lose. He’d legitimately freak the fuck out
Based on that bit in the original script about a former fiancé for Lee: The relationship happened when he was younger. Think 'Police Story era Jackie Chan'. He was with her for 5 years, and she thought that he was just shy. Maybe once the engagement hit that things would change and things would fall into place, he’d wind down and start taking less cases. That did Not happen. He still feels bad about it, because he was a cold romantic partner.
Carter takes Cantonese lessons, because he does actually care about being able to talk to this man. Once they're in a relationship, he starts trying to flirt with him in the language and Lee is MORTIFIED “who taught you that?! Do you even know what that means!” “Yeah! I said what I said!” “You sound like a dirty old grandpa!”