"...I have so many questions about first of all what a soul even is, but secondly what happens to that soulless body, I'm guessing it's unharmed but nonresponsive?  If only there was the infrastructure necessary to run a fMRI machine...Probably not in this lifetime, it'd be way too specialized.  And do the physically-eating-you monsters take bites of your soul, too, while they're at it?"

"All demons eat souls," repeats the chemist patiently.

"...Yes.  That's a given.  I mean is them grabbing a limb and chomping going to take a bit of your soul with it, if you know.  If you can know.  I'm - not sure how you came to the conclusion that souls exist, let alone that it's souls that demons target - it was a hotly debated topic whether they existed at all where I'm from, or if we were simply a sack of self-deluding chemicals - but if I assume that souls exist, then yes, sure, demons eat them.  The question is what other interactions souls have."

"- souls don't come in bits. Uh, what... do you think happens... when people are mentally fatigued."

"Well, their capacity for doing complex or creative thinking decreases temporarily, and they probably need to do something else or just take a break, but...it's mostly just that they are in fact mentally fatigued?  What happens here?  ...It's bad, isn't it."

"You can't offload mental fatigue onto a mouse, they aren't smart enough to support it, you can only do that when you're physically tired. This is why people have cohabitors, so they can rest without sleeping."

"...That does not make sense; you're still on the same brain, it's a chemical, neurological imbalance as much as it's a problem of thinking - oh.  Standard cohabitancy is troportation-induced, isn't it.  Which still...doesn't make this make sense...but makes less nonsense."

"- what, how did you think it was done?"

"Well, mine's all-natural 'people sometimes spontaneously happen in my brain', and there's people who actually made guides to meditate and visualize your way into growing someone, and sometimes extra people just happen as a trauma response.  But if you have two brains per brain, somehow, that's...less of a surprise, that you can refresh fatigue by plugging the other person's thought-pattern in.  We'd just have to task-switch.  ...Wonder how that works for muscle memory, actually."

"...we have one brain, two souls."

"Okay, so...Brains, their physical structure, that actually contains data.  Is in fact the person, their thoughts, their memories, as far as I know.  That's why head wounds suck.  And separately, there's the neurochemical-electrical impulses that are what day-to-day consciousness is.  Somehow, the troportation that sets up cohabitation is compacting the data stored in two brains, into one skull.  If you don't have co-consciousness...Well, I could come up with a lot of possibilities for how the fuck, but that's rather premature considering no way of checking safely exists, and neither will it anytime soon.  If you ever do operate your brain at the same time as your other half, then I'm stumped on fatigue-reduction again and confused about data-storage."

"...why in the world would you assume, having come from another universe that doesn't have troportation, that 'as far as you know' is far enough to make pronouncements like that, in contrast to what I'm telling you, which is that after I've been awake for another six sands I'll be unconscious and my cohabitor will go to his job at the tavern, and that before we were cohabitors we had separate bodies brains and all?"

"Well I didn't have a soul yesterday, and - does brain damage exist?  If getting hit on the head doesn't sometimes fuck up people's cognition that's evidence against physical brain encoding!"

...She's frustrated for the first half, and then, when she hits on 'does brain damage exist' as potential falsification, she veers into excited science mode!

"And I'm not disputing your experience of cohabitation, or that consciousness is a troportable quality!  Just and only that there's a specific thing called a soul involved, because it's underspecified and poorly-evidenced!  Make falsifiable claims!  That's how you do science!  And I've inherited knowledge from lifetimes of people doing exactly that thing, that haven't yet been outright wrong, save where they lacked information, except in the parts that they already knew didn't make any sense!"

And now she's frustrated again.

Someone else shifts in.

"Excuse me.  We're going to take a minute or three - a centisand, or thereabouts - and cool off; getting that aggravated at you was profoundly uncalled for."

"- okay. You're, uh, swapped in at the same time?"

"Something like that.  She would have said cohabiting, were she coining a term, but she isn't coining the term, so she won't.  On Earth, where we come from...if the comment Ophelia - who is not your previous interlocutor; she still needs to pick a decoy name if she's actually expecting this conversation to end up on an alternate Earth's Internet, authored by her own alternate universe hand - if the comment Ophelia heard, about having to leave notes for other halves, is indicative of cohabitation's nature, you would be described as a fully dissociated system; the only thing you share is a body.  By contrast, we're most likely what Earth called a median system; it's not inaccurate to say that all of us are present all the time - it's just that we have our own separate areas of concern.

"You were speaking with the one of us who spends the most of our time by far fretting about correctness and seeking to contribute to the accumulation and spread of knowledge, and the implication that what she had spent that much time and effort acquiring was useless in the face of, to our perception, a statement of 'indivisible, apparently-incorporeal, fundamental-to-consciousness souls exist because I said so', hit her right in the pride.  She doesn't actually have much of that, so she clings fiercely to what pride she has.

"Also, she does legitimately want to know what happens with traumatic brain injuries here; some possible outcomes would actually potentially disprove the hypothesis that brains store people-data, and, for that matter, be potentially evidentiary for the 'are brains' neural patterns merged, or in superposition, post-cohabitation' question if souls' existing ends up not being parsimonious based on the available evidence; she really wants to find that out, if any way exists to check without personally concussing someone.  None of us want to hurt anything - except monsters, and that drive is mostly Diana's alone, anyway.  She's outvoted.

"I hope that helps explain what's been happening; while we're thinking of it, might I ask your name?  You may call me Sylvia, and I'm sure that if you ask, the science lady will figure out something to call herself once she's driving again."

"I'm Wheat. Uh, I don't know very much about brain injuries, seeing as I am a chemist. I assume they get healed off like other injuries. We're never awake at the same time," says the chemist, looking dubious and overwhelmed at the monologue.

"Yes, that's not exactly your field of expertise, our apologies.  We've never really been able to specialize knowledge-acquisition very well; almost everything is interesting to hear about.  This is probably going to be a recurring problem in hypothetical uplift plans, because - well, a certain someone -"

" - Call me Mira, I suppose! - "

"Well, she's prone to going off on infodump tangents at the drop of a hat, and that's not just a her thing, as you've noticed."

"It's very conspicuous," says Wheat.

"Isn't it just."  She laughs quietly, a self-deprecating chuckle.  "That's actually another of the non-normative things our brain and-or consciousness does, in addition to the spontaneous people-ing; it seeks opportunities to give or consume infodumps.  Regardless, you're not a psychologist - someone who makes a study of the ways people think, in case the profession mistranslates."

"I am not," Wheat agrees. "- the extra cohabitors appear spontaneously?"

"Well, there's usually - we sort of do make them up first - "

"But, yes, we simply coalesce at the appropriate time and place, given the appropriate stimulus.  It's somewhat of an open question, to our attempted amateur psychology, whether this is generative, in our case, or simply assigning extant personality traits to names, faces, made-up or dreamed-up backstories...imagine a child with some imaginary friends that stuck.

"That's not totally accurate, but it is rather catchy."