Yeah it's SUPER cool!! I was fascinated before finding out we were plural ourselves and I'm still fascinated, honestly. :3

Yeah we're pretty much siblings that happen to share a brain! It's weird and cool and awesome.

We personally have shared memories, so if someone else does stuff and then I switch back in, I remember everything they did as if I did it. Which can be... disconcerting sometimes, to say the least. You get used to it though. Just gotta remember who was doing what...

Not everyone has shared memories though, there are other systems where everyone has separate memories walled off from each other. It's gotta be awkward to switch into front and not know what's been going on over the past hour/day/month or however long it's been! But on the other paw that means it's at least theoretically possible to keep secrets from your headmates, which hah, that would NOT work for us. No surprise birthday parties or anything!

"headspace" is kind of orthogonal to plurality, by the way; you can have one if you're not plural, too, and not all plural systems have one. We still only kinda-sorta have one, and we didn't start with one, we had to try and make it. Anyway it's basically just like, a place to imagine yourself in, I think. Like a VR-social space type thing but in-head.

(We had virtual bodies before getting the virtual space to exist in, though. In fact that's how I found my first headmate, getting little mental flashes of her in my mind's eye. When we're doing virtual bodies but not picturing ourselves in headspace we're usually either in nothing in particular (you know how in dreams, anything you're not focusing on isn't there? like that) or situated in the physical world, with whoever's "in front" (controlling the body and everything) "seeing" other people around, on furniture or whatever (not literally seeing, more like imagining them there).)

-- Frost