David looked at the clock. His wife would be home from work after another hour or so. If anyone would be a good test subject for the Sentienator, she would. However, only ten minutes into waiting, his boredom and curiosity was getting the best of him. He was considering testing the device out on himself. It was a little risky, though. Although the instructions mentioned what the device did, it didn't go into detail of things like whether the sentient body part would have any control, the ability to talk, or anything. Still, it wouldn't hurt to at least look over some of the options.
Host body... only his was listed. The range of this thing must not be super great, if it can't detect anybody in the neighborhood. No idea whether this thing worked exclusively on humans or if it could work on animals, too. Well, with him being the only current option, he might as well select himself.
Target body part... the list of potential body parts was impressive. Arms, legs, hands, feet, his tongue, his eyes, his heart... that last one was a scary idea. Definitely avoiding that one. As he was looking through the options, his dick started rising at the kinkiness of having a sentient body part. He briefly chuckled at the idea of his dick having a mind of its own, but decided it already had too much of one for his liking. Instead, he settled for his butt. He was wondering how his butt would take to being sentient. Would it resent its place in life, being sat on, and used on the toilet?
Intelligence... this was a simple slider, only for the body part. On the far right was human-level intelligence. On the far left was simple intelligence, likely having awareness and base instincts, but little else. David left the slider at the far right, curious how a human conciousness would adapt to being a butt.
Personality... once again, this only affected the body part. He figured it was probably a good thing that the host could not have their intelligence and personality changed. Along with a list of custom options, there were some presets, including obvious things like dom and sub, as well as others such as perky and snobbish. That last one was definitely a no-go. The last thing he wanted was a butt that thought it was better than him. There was also an option to copy his own personality traits into his butt. He laughed at the idea, but decided to go with that.
Noticing that the individual traits could be modified from there, he decided to look over them, curious what the Sentienator thought of him. Somewhat caring, lazy, curious, a bit of a clean freak... better lower that stat a bit; some importance is needed, but he doesn't want his butt constantly grossed out at being a butt. Slightly dominating, better also lower that. Not too much, though; his bottom doesn't need to be a complete "bottom". Honest, slightly impatient, easily bored... life as a butt would probably be boring on its own, so maybe make his butt not so bored. Good sense of humor... that one's important when you find yourself living life as a butt, so keep that the same. Hopefully, that humor doesn't consist primarily of fart jokes. Wisdom... he was a bit surprised to find that this was below average. He kind of wished that he could alter this stat for himself, but at least he could add some wisdom to his butt.
From here, David skimmed through the rest of the personality traits, until he eventually reached the bottom of the page, where there were were two buttons: Apply and Cancel. David looked at the clock; there was still over 30 minutes until his wife came home. He could probably wait until then and try the Sentienator on his wife, instead. But at the same time, half-an-hour was just enough time to get a good sense of how this thing worked, and maybe make some more changes if needed.
Hovering his thumb over the Apply button, he only hesitated a moment before pressing it. As he did, though, he glanced up the screen and panicked when he noticed the last pair of options he had glossed over: Awareness. And the awareness for both himself and his butt were turned off.
The app refreshed as it completed its function.
David suddenly heard a voice similar to his own. "Is everything okay?"
David shook his head. "I don't know. I was fiddling with these options and I think I clicked something by accident. Are you okay? Are you still you?" David sat up and poked at his butt.
"Yeah, I don't feel any different. That's you poking me, right?"
"Okay, good." David relaxed and gave a sigh of relief. The functionality of this Sentienator was interesting, but he didn't want to do anything to Mike, yet. They're practically the best of buds, having a symbiotic relationship of sorts.
David remembered when he was little, it seemed that his parents had trouble getting him potty-trained. Despite their instruction, David simply could not control his bowels. One day, David decided to ask the voice in his butt if it could control itself. The next potty-training session was a successful one. David's parents were so proud of him, and David exclaimed that he asked his butt to and it did. His parents thought it was a very cute statement, unaware of its truth. Although David's butt could communicate with him, it only did so mentally. Despite having human intelligence, David's butt is physically just a butt, with no way to physically speak, as well as no sense of sight or hearing, nor smell or taste.
This made it impossible for David to convince his parents that his butt was a person. Growing concerned, they first sought psychiatric help, before eventually seeing a priest. In an effort to expel the "demon" that had "possessed" David's posterior, the priest tried spanking it out of him. For David, this was painful. For David's butt, this was traumatic. David's butt soon convinced David that he shouldn't tell anybody that his butt was a person, anymore. David agreed, but promised his butt that he'd always consider it to be a person and his friend. As part of this promise, he gave it a person's name: Mike.
And so, that was that. Growing up, he never again spoke to anyone of the person living as his butt. Even now, being a married man, his wife has no idea that she had married two people in one. He also learned the importance of honesty and care of other people, as being a troublemaker would also result in more spanking for Mike. The importance of cleanliness was also attributed to the importance of keeping Mike clean.
Now we return to present time. David looked at the device in his hands. As far as David and Mike were aware, Mike was simply born as David's butt. Possibly the only people who were born this way. Now there was a device that could give sentience to other body parts, to David as well as other people. If there's more than one device like this out there, there might already be more people walking around with sentient body parts.
Mike had taken interest in the device, as well. His whole life, he had been David's butt. Lacking any of David's many senses outside of touch, his sole purposes in life being to be sat on and expel David's waste, isolated from the world outside David's body. All things considered, he didn't hate his life. It was the only one he knew, and David had treated him well as a butt, almost like a brother. He also felt pretty special, living life as a body part that, as far as he was aware, nobody else had gotten to live as. And though he had no sense of the outside world, David had done well to help explain it, tracing a finger onto the butt as a way to describe shapes and actions. But sometimes, Mike wondered what it would've been like had he been born as a different body part, or even a whole person.
25 minutes until David's wife got home. David and Mike contemplated the first thing they should try with the Sentienator.