I would say ‘hooks’ make a good background.
A hook is a feature which can latch onto other players’ plot. Maybe it’s a goal - you have always dreamt of being the Imperial Ambassador to Dubhtraig - or it could just be a trait like never backing down from an insult. It’s something you say or do which makes people stop and go ‘I want to drag this player into my story’ because you seem like fun to the player, even if it’s because their character would hate you.
For example, my character writes pamphlets about the Anvil Hospital growing stagnant. The Anvil Hospital is a well-established and useful institution which is probably going to be around until the system ends, but it has created game for me because people drag me into their own stories; a couple of hospital staff wanted to know more because (I assume) they want to make the hospital better, one person wanted to talk to me about helping to fund a psychiatric hospital, another person walked up to me and flat-out asked how much money / granite I needed to make the medical school I was ranting about at that event.
A guild-mate wanted to be a politician and that meant lots of running around trying to make friends and maybe to apprentice under an existing one. He later went on to decide he wanted to marry a woman in another nation (after getting permission from her player) and that led to all sorts of wacky hijinks including getting beaten to a pulp by her IC dad, promising to kill an immortal being and bring its head back, then finally going through a bit of a quest to change nations.
In both cases, those little hooks gave the characters a set of goals, a vague idea of how they might go about reaching those goals, plus a lot of complications that other characters could throw in their way or help them to overcome.
To share a hypothetical situation I heard once:
Four larpers walk into a bar looking for a ranger. In the corner is a brooding figure who sticks to the shadows, smoking a pipe, and glares at people as they walk in. At the bar is a ranger with a pint in hand who is loudly telling the unbelievable tale of how they slew a dragon with a single arrow.
One of them is offering you information about themselves and giving you an easy way to join their game, the other is not. They are offering you ‘call my bluff’ as a hook. They are offering ‘buy me a pint’ as a hook. They are inviting and hard to ignore. The other one… they are less inviting and easier to ignore.