Eugene may look like a greaser but my theory is that he's just a poser and in reality just a big nerd. :3 I like to think that Fuchsia is into punk and alternative music because of her crazy fur color and earrings. Also I have a theory that all the female kangaroos are single moms since there's no dad around.
There's this crazy theory that was on tumblr where Lucky is actually walker after getting into some kind of accident. Like if you add up the numbers on their shirt its 90 and in japan the number 9 means pain and suffering? Idk.
It's more so for my village's Diva because of things she's done, but I'm convinced Diva is some sort of mass murderer, mafia boss, or criminal thief mastermind, considering every time she gives me something, it's from her "friend" who has a storage and was clearing it out, or she whispers "whew, thought I'd never get rid of that", and she's the ONLY villager I have that does that. I mean, I know any villager can say that, but still. Thankfully I seem to be on her good side because she almost always gives me medicine if I happen to get stung by a bee, and I've gotten a lot of bells from all the things she's given me. Hey, I'm not gonna part of some mayor scandal and get caught by Copper holding some blood soaked shirt from one of Diva's crimes.
Frank the cranky eagle used to be a world champion boxer and between the events of Animal Forest and New Leaf he retired and became a cranky old coach instead.
This would explain his boxing themed house and his personality switch from a Jock to a Cranky.
Here's another one:
Tex the smug penguin is or at least was part of a heavy metal band.