The "brainspace" refers to, well, my brain. I often say that my brain and I are not the same person, that he is too creative for my own sake. And that is true. My brain and "I" are separate. Sometimes he speaks to me, gives me instrucions, but most of the time he keeps to himself.

But if my brain is a different entity from me, then what am I ? I've been calling myself a carcass for a long time. That's how I see myself : a disembodied piece of meat with some bones in it. I am thankful to my organs for keeping me alive.
I do not feel connected to the concept of humanity.
But then, how do I exist ? Good question, sometimes I also wonder. I mean, I can hear my own thoughts, I am conscious most of the time, I am not entierly brainless.
But what is this page about, exactly ? Well, since I am talking about my different universes, I need to explain how I think.
I have two types of characters : projects charcters and headworld characters. My project characters were made specifically for a project, such as a video game, comic or other. They are technically OCs but I don't necessarily consider them as such, though that doesn't prevent me from getting attached to them. Headworld characters are, well, not exactly characters. They're more like actual people who live in my brain, and I happen to look at what they do from time to time. These different headworlds have varying levels of "realness" too, and of course I am aware that these are figments of my imagination and that, ultimately, I am the one deciding of my character's actions. Mostly.
So this page will explain how these different headworlds work and how I represent myself !
So there's this thing called a "sona". Basically, it is an avatar used to represent oneself, under different circumstances. There are different type of sonas too : fursona, truesona, kinsona...
I have several different sonas. There is my fursona, Nethal, my most important character emotionally. I originally created her because I needed something, someone to project myself onto at one point in my life, cuz things were difficult. Now, things are much better, but Nethal is still here. We are indissociable.
Nethal has several variants too : Nethal the spotted hyena, which is her lore-accurate "base" form, what is the closest thing to a truesona to me. Then, there are 2 AU, Dreamverse!Nethal and Cyberscape!Nethal. Dreamverse!Nethal is the hyena/dragon hybrid that I often use too, it is my fursona as much as regular Nethal. I don't use Cyberscape!Nethal as much cuz this AU lacks development, yet.
I have two other fursonas : Toxyk, my secondary fursona, and Dr. Skolopendrite, my tertiary fursona. Toxyk was the first ever fursona I made, but ended up never using him. I decided to revive him now that one of my headworlds is taking more importance, but I don't really use him to represent me... Maybe he'll stop being a sona someday, but I'm still attached to him as of now.
Dr. Skolopendrite is just here for funsies tbh. I love him.
Then, there is Em, my humansona. I've never seen someone refer to a sona as a "humansona", but I like it. She kinda is multitasking, being both a cartoonified version of me, an Invader Zim AND a Psychonauts self-insert.
I do have other fandom sonas/self-inserts. There is Cloud Night, my ponysona, and Eliot, my (dreamworks) trollsona. Em technically could work as a human homestuck oc, I think I have her potential chumhandle somewhere in my troll ocs notes.
For my comfortsona and kinsonas, it's a bit different. They are oc-ified pre-existing characters. Also, for my "kinsonas", I don't exactly "kin" these characters, nor do they represent me that much yet ?) but they are still important to me nonetheless. My comfortsona is a furryfied version of Beetlejuice, and my kinsonas are ocified versions of Tenma Taro (Ace Attorney 5) and... I believe his name is Hooky in english ? It's a fake robot lizard from Monster Buster Club. I clearly remember the first time I saw his design. I was so enamored with it, it was literally the coolest thing I've ever seen... Still currently trying to work and finalize the designs for these guys, which is why I've never rlly talked about them anywhere as of now.
Alright, now that "me" is explained, Time to explain the different layers of headworlds. I have 3 layers : primary, secondary and tertiary. They primarily refer to how long I've had them. My two primary headworld, Keep On and The Life of Fango, are the most important ever for me. Secondary headworlds are a bit trickier. I've had them three since middle school, and they are still being worked on. However, one of them, Fun Zombie Apocalypse, is nothing but a cool concept. i could never design the characters, therefore I simply... don't really go there. I've been thinking about pushing it down to tertiary or simply discard it, but I can't bring myself to... Jack and Jill is pretty developped, I'm not currently working on it too much but I ike it. Mad Lab Monsterz, however, is the one I'm currently fixated on, and that is really getting developped. I'd say, if I had to move one of them to primary, it'd be this one. Tertiary headworlds are the most recent, and really REALLY need development. I'll mention one, Redemption, that I rlly like and look forward on expanding.
To conclude, my three "main" headworlds are Keep On, The Life Of Fango and Mad Lab Monsterz.