Delicious, finally, a good question. I have a few theories, all working off the base assumption of a soul as a form of shaped energy. Personally, I think it exists within the body, during times of life. Not in any specific part, and anything that may take off part of the body doesn't take any of the soul with it. It's sort of like the thing where losing a limb makes the other ones stronger due to having the same amount of blood and nutrient intake in a body that just lost a hefty chunk of mass. Still got the same amount of soul. Obviously not something I've tested, since emotional experience is a soft science, there's the emotional trauma of losing a limb to account for, potential of undiagnosed body dysmorphia skewing results, and there's the ethics of taking someone's limb off to observe. Sadly something I don't think ever will be tested, since anyone who's throwing ethics out the window to do it is probably also ignoring all the other above issues.

Holy hell, that was a tangent. Anyway, I believe the soul is the force controlling the body. The specific shape and proclivities of each given soul isn't something I've thought much to categorize, even broadly. It's definitely a thing that can change over the course of time, as things do. One can even change it themselves, if they were so inclined. I've had a notable impact on my own, as have outside influences I've surrounded myself with. It's different than an impact on one's brain, this I know. Relating to the outside influences thing, I'd advise you all at home be very careful who and/or what you pledge your soul to. Make sure the changes you experience are ones you're comfortable experiencing. Be those changes in line with your own self-image, or what amounts to ego suicide, know what you're signing up for.

I'd be the victim, ideally, and let me break it down in every step of the thing:

-The kidnapping itself:
I'm chilling inside, late at night. I need to use the bathroom, so I get up to do that. I think I hear something opening, but I convince myself I'm probably being paranoid. I clean up, head out of the bathroom, and I see a blur at the edge of my vision before a sharp pain and a loud ringing. Before I get my wits about me, a gag gets shoved in my mouth, and several more blows to me get me disoriented enough where my limbs get bound up. I get dragged out into a van parked just outside, and told to breathe deep as a mask hooked up to a machine goes forcefully over my face.

-The first few days
I wake up in a not bad looking basement. My captor walks down, looking happy to see and have me. I'm tied up to start, but I get let loose with a shock collar, and the understanding that if I'm seen upstairs or if I try to tamper with it, I'll end that nonsense back down here, with a couple new twitches for my trouble. The basement's cozy, though. Very early 2000s. A PS2, a big CRT to play it on, a couch with a cot inside it, a chest freezer, and a microwave, among other things to make it long-term livable. I'm cautious enough about using it all early on where my captor pretty much has to force-feed me and make me play some of the games, starting off with ones I know decently well, and pushing me very hard to talk about them. I'm scared, and probably somewhat spiteful, but they seem very happy.

-Long term
As I settle in, I get less scared about using what's given to me. I start getting a more positive opinion of my kidnapper, and they start letting me upstairs. They mandate that we spend time together, doing things, playing games, watching movies, sharing meals. Eventually they let me up in their bed, and at this point, I associate them so much with all the positivity they've filled my brain with that it makes me smile to accept. It reaches a point where I'm just latching onto them tight, and the very idea of "escape" feels like horror.