Wildest fantasies...
Building an M/S dynamic that I'm literally not allowed to get out from. And what I mean by that is being monitored and kept in such a way that I literally can't get free, and an escape attempt would just cause me to be locked up in the house.
Not being used sexually against my will exactly, but having it so that my will does not matter either way. So maybe I don't want it to happen, maybe I do, but either way, it will happen.
Being forced to be a chore slave. Making food for Master, making coffee for Him, keeping the house nice, ironing clothes, etc. Basically, unless I'm sick and genuinely medically require rest, I should more rarely have a break. If I get better and faster at my tasks, that just means I now have more time for something else.
Forced chastity and denial... permanently. Being caged by or against my will and having to downsize all the way to a flat cage. The only time it should ever come off is if it is causing medical problems or needs to be cleaned. Oh, or if people who didn't consent to see it would see it. Never getting any sexual release, ever. I am a slave, I don't deserve that. I'm lucky to keep my cock and balls at all. That's paired with having to get Master off at least once a day.
Water/fluid play, as part of humiliation and domination rituals. Having to drink His piss, swallow His cum and spit, as a means of dominance and humiliation. They would either have to be consumed plain, or they would be added by Him to my food or drinks. I'm not into fluid play, but I am into the idea that another man has the power to make me drink his piss, and I'll have no choice but to.
Bondage. I'm not into bondage in quite the same sexual way as others are, but I am indeed interested in it sexually sometimes. But to me, that's not its core purpose. I'd like being penetrated while allowed to struggle in bondage, yes. But it has non-sexual uses, like literally just being used to detain/contain me. Master wants to pretend I don't exist, I'm in a chair with my hands and arms roped to the armrests, my legs to the chair legs, and my body to the rest of the chair. I'm blindfolded, I have something that makes it so I can't hear, my mouth is gagged and probably taped, and I'm just in some random corner for however long He wants.
Total isolation. Being made to totally isolate from any friends or family, having any means of contact taken from me, or having Him control my means of contact entirely... Not to say I shouldn't have any friends or social life, but I should be able to easily separate from that. That's incredibly empowering for Him. It cuts all of my power to protest or reach out to someone and hands 100% of my reins to Him. He could do all of the above to me and more, and I could be absolutely unwilling, but this fundamental means of control means He has the full power to make all of that happen anyway.
Body modifications. I used to be more hesitant when it comes to modifications, but I've changed a bit since then. I'm a firm believer in branding, up to and including hot iron branding. Piercing, hair removal, hair colors, tattoos, neutering, etc. (You can't choose to be straight up neutered without a valid medical reason, actually, but it'd be cool to try and find a way if me and Him wanted that.)
Dynamic. All of the above is very interesting to me, but so is Master also being a regular romantic partner. Ideally, my dynamic would never truly stop or pause, but there would be times when not much is happening in the way of power exchange. Title and respect would ideally be permanent and ongoing. What I mean by that is, I'd never just call Him by His name. I would ideally always be required to use Sir, Master, or any of the similar. But under that, I want to be able to do regular boyfriend things. Go for a walk, sports/hobbies, cooking, etc. Not just for me, but I think He also deserves to feel like He is with a human and partner, too.
That is all fantasy stuff that I realize can't all be happening all at once. Some of those things may not ever happen. One or two isn't technically possible at all. But it'd be cool if they could be explored or considered. Perhaps brought as close to reality as they can be.
I also realize that this isn't everyone's cup of tea. In fact, there may be around like fifty people in the world who actually like this stuff. The rest may condemn it as abusive and impossible, but they'll never actually get to see what happens.