I've been thinking of questions for OCs to ask to nail down their archetypes, things they enjoy, the stuff they can be defined by, etc. but after some consideration, I've realized that you only really need one question for them to answer:
"What do you live for?"
Or, if you're like me;
"What do you fight for?"
It's such a simple question, but if you answer it correctly, you can clearly outline everything that your character encapsulates. For example, my own OC, "Michael", would answer it like this:
"Well... I mean, I fight for a lot of things. I fight for my games, I fight for my mom, I fight- well, I fight my mom, because she's so nice... I'd, uh... I'd fight for the pizza place I work at, because it's treated me really well over the past few years... Yeah, I, uh... I deliver pizzas for them. Um, but mostly, I fight for the thrill of fighting, y'know? It's just nice to find solutions to problems that you didn't know had solutions in the first place."
In just a single paragraph, Michael is defined as a timid nerd who enjoys video games, his mother, working as a pizza delivery boy, and just the thrill of fighting as a whole.
You don't need 20 plus questions of favourite song, favourite food, favourite place, etc. All you need is just a single paragraph describing what your character lives life for. What they wake up every morning with a smile (or bored expression) on their face for. What they go through the struggles of the morning for. What they go to bed and pray that they get to wake up another day for.
I really wanna see this concept explored more in other people's characters, so if you're reading this, why not try to answer the question yourself? Give your character an entire backstory in just a single paragraph.
Because that's a pretty fun deal. :D