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See The Laundry Series. In that 'verse, demons are energy beings from another dimension; summoning them means they need somewhere to inhabit. And, the thing about neural systems...
Once safely ensconced in a human brain, level two through four entities can happily reside in our reality indefinitely. Most of them can also jump from one body to another and gladly do so, unless restrained by a geas or other binding. Tattooing a body with such a geas or surgically implanting a small titanium plaque containing the geas before summoning an entity into that body is highly advisable. The only other options to inhabiting a person is inhabiting an animal or a corpse.
Only level two and level three entities can inhabit corpses or non-human mammals. Level four entities can only possess creatures with complex, fully intact neural structures. However, entities like the Feeders in the Night can inhabit almost any mammal, dead or alive, and a few summoned beings can only inhabit animals.
One of the more disturbing facts about possession is that some of entities physically transform the creature they are possessing. The exact details of how and why this process occurs are matters best left to half-mad theoreticians, but the practical fact is that after an entity has inhabited a body for somewhere between a few days and a few weeks, the body often begins to transform, becoming something strange and disturbing. Such transformations can include growing poisonous fangs, scales or similar details of appearance. These transformations do not change the basic shape and structure of the possessed individual – a possessed human will always remain an upright, four-limbed biped. However, it can transform someone into something truly hideous. Also, these changes usually persist after the entity has been banished from the body.
edited 23rd Aug '14 8:09:25 PM by SabresEdge
Charlie Stross's cheerful, optimistic predictions for 2017, part one of three.
That sounds exactly like what I'm working with for the most part. Thanks a lot, I'll take a look at them.
Nerve cells can get exhausted like any other part of the body. If they use up their stores of certain things, they stop working properly, and if they go too long without a chance to "cool down" and fire up the self-repair systems, stress will overwhelm them...they effectively burn out.
Reality is for those who lack imagination.
Alcohol-related drunkenness tends to cause a lack of impulse control. That's pretty 'amoral', yeah?
Or did you want 'immoral'? That's something better suited to Heroin withdrawal.
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Either/both.
The specific behavior I'm looking to cause with this character is general aggression and something close to what I think manic-depressive disorder is like. The character is a possession victim who fought the possessing force off late into the phase where biological change is made to the subject.
I've been doing a series of monster-hunter stories and I felt like doing it form the other side as well.
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The basic premise is that they're Lovecraftian-esque energy beasties from elsewhere. In some of those elsewheres, the time base is thousands of times faster, meaning that something that isn't sapient or sentient can pretend to be so by sheer brute force. An energized summoning grid (or pentacle if you're old-fashioned) can call them into our dimension—and you'd better have a larger containment grid around the inner summoning grid, or it'll flood-fill the closest suitable host.
Stross thought this one out: they're things of energy. So that means they can spread by conductance, and human skin is conductive, meaning that an infectious outbreak of fast-thinker soul-eating entities is entirely possible if you're stupid or careless enough. At the same time, they're susceptible to electrical charges, so tasers or shock prods do a great job of banishing them back from whence they came; even better if you modify the generator to output a coded signal pulse instead of white-noise energy. And possession by a demon is an extremely serious matter, assuming you survive; the RPG sourcebook I quoted from assigns permanent SAN damage to anyone who's possessed and survives. (Most of the time they eat your mind permanently instead.)
Of course, that's just the basic preta zombie-maker. More advanced demons might be able to permanently install a presence in their host's mind which would affect their behaviour, or do other nasty tricks like that.
Charlie Stross's cheerful, optimistic predictions for 2017, part one of three.
It would help to know a bit more... Permanent, temporary, or ongoing-but-reversible, for example. It sounds like you're looking for the mechanisms behind recurring violent psychotic outbursts, and I'm not sure how that connects to Bipolar at all. Those outbursts seem to be related to dopamine production in those with schizophrenia - but not all that much outside of it.
There's PTSD, and depending on the character's background that might be something the outbursts could be confused for.
The 'winner' here might be methamphetamine... though if you go down the list of side effects it has, it seems like it'll cause just about everything in the book. If ever there was a 'demon drug', meth is a good candidate.
You risk (literally!) demonizing the mentally ill with a comparison to an existing disorder as well, and I'd step away from that. On the other hand, Demonic Possession that explicitly masquerades as a mental disorder is a good source of your daily dose of Nightmare Fuel, so there's that.
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Tim Powers did something with that in Earthquake Weather: some cases of what looks like multiple personalities actually is someone playing host to a ghost or two. Or more, in some cases. They're not distinguishable from someone suffering from ordinary schizophrenia unless you know exactly what symptoms to look for.
Slight nitpick, but dissociative identity disorder (formerly multiple personality disorder) and schizophrenia are two different things.
The latter may be present in someone with the former, but schizophrenics don't necessarily have DID, which is comparatively rare; DID likes to bring friends to the party, so someone with it often has other disorders.
About demonizing the mentally ill. I did think about that and I'm making it very clear in narrative that, although possession can look like mental illness, it is very different. The hero antagonist makes a big speech about having to confirm an actual possession before doing anything, and that going to a psychiatrist is a much better first step than calling the church.
I only really said Bipolar because I'm still iffy on the details, hence this thread. But I'll be sure to research the effects of meth on the brain, thanks.
As for you first question, I'm still not done with even my first test-chapter, so it's still a bit muddy. What I do have is a killer with a demonic physiology(though she can morph to the point of looking passably human) and enough restraint on her attacks that she only targets people she thinks won't be missed, only because she feels their deaths won't be linked to her. Of course, I doubt all of that will still be the way it is when I'm done, but it's still early enough that I don't mind changing what seems off. I still don't have a reason for her desire to kill other than she wants to, and I'm not satisfied with that.
A forced Jekyll & Hyde, then? Her 'Demon' state targets people because they won't be missed.
More like a dexter thing, if the five minutes I've seen are an indication of the show as a whole. She knows what she's doing and just doesn't care except to the point of avoiding getting caught.
I've also been playing with the thought that she might think that's why she's targeting them, but really it's just an implanted instinct to kill people who would be going to hell. I'm mostly not sure about this because it would mean firming up what exactly the line is between sin and not sin in this universe, something I managed to avoid in the past by having the main religious sect in my stories not having the concept of sin in the same manner as traditional religion.
Essentially, I'd like some help in figuring out the pseudoscience behind my story's version of demonic possession. In short, what kind of brain damage or abnormality would cause the kind of amoral behavior associated with demons?