Then again, I've had to deal with my hubby's delusions (no, seriously; he truly believed a lotta stuff, including truly believing he saw celebrities and political figures around town, plus he also truly believed one alternative recording artist had several bots around, just waiting for him to find them).
So, writtenwyrdd's post on this syndrome, called Delusional Misidentification Syndrome, piqued my interest in two different ways. One way is noted above.
The Second Way - And, Yes, It's Related to Writing
When anyone decides to write fantasy in any of its many genres, we generally write about beings, etc., that are figments of our imagination or are taken out of myth: Think vampires, think gods and goddesses of different cultures.
For instance, in my current WIP, I have a minor Roman goddess transporting the MC back in time to the 1940s. The MC wants to find her birth mother, and, as a goof, decides to petition this minor goddess, since everything else she's tried hasn't helped.
Of course, the goddess helps her. But how does she react to the goddess?
Since she's in her old bedroom in her adoptive mother's house, there's no one except her to react to the strange goings-on. And she freaks, naturally; who the hell wouldn't, especially when she opens up the bedroom door and something (not the goddess herself) is not quite right out in the hallway... ;-)
The twist I have is that another character sees the goddess in the flesh. The MC figures she's going to get that character - that the other character is going to faint dead away.
Except, the other character doesn't.
Which makes the MC almost faint.
There's another story there, but I ain't tellin' it. Might turn into a prequel of sorts (if I can just get the damn story in the shape I want it to be in).
But I digress.
So What's This Syndrome All About?
I'll writtenwyrdd describe it briefly:
The nifty thing about DMS is that describes a bunch of monoschematic delusions, which is to say, that they think one thing is changed in the delusion and otherwise reality is pretty much normal.
I have a fantasy tales from around the world book at home, and at least one of the stories is the old chestnut about a woman giving birth to a perfectly-normal baby only to look again in the morning or whenever and see that it looks differently.
Ah, yes, the changeling.
The story I'm thinking of is from Ireland; the basic idea is that sometime during the night or day someone that the mother pissed off in faery (or wherever) decides to get back at her by taking away her newborn and replacing it with a changeling (looks similar to the human babe but not exactly).
Something excellent that must be considered by fantasists. Because, let's say a vampire pops up in front of a cop on the street: How is that cop going to react? How is the MC going to react? Others can react in different ways, too, depending on their backstory (as noted in my own example).