So, I've had this idea in my head for a little while and have decided to write it down and see if anyone catches it and wants to play it out with me.
Lately, I've been into slight body transformation, male pregnancy, aliens and pony boys so this idea is based off of those. If you have no wish for those things, then it's best to close the tab. If you do however, read on I am also willing to do this with a demon too, and the demon is hunting for his human mate in the same circumstances as below :)
This idea is going to be an alien race (your character is a part of) that is only male. There is no such thing as a female. They can only mate and reproduce with human males so when the alien comes into it's mating age, it goes down to Earth and picks a male mate to take back to it's planet. This has been done for centuries and many humans populate this planet as a mate to the alien. They do not have free will though. They are like slaves.
This alien race take the human back to their planet where they have grown female reproductive organs of their own kind. They operate on the human's back, and insert the new organs before letting them rest for a few days. Then training begins. They are taught to listen and be obedient. And this alien race are big on having thier mates decorated. Their mates looks are important and their status is based on this. When their mate first comes to their planet the size of their cock is judged. If it needs to be thicker and larger, then it's made to happen through various tools. A cock ring is placed on the organ to keep it hard and standing at all times.
The mates are turned into pony boys after their first mating session. They are giving injections into their 'breasts' to bring them out a little for the chest plate. This alien race love 'horse' racing. And their mates are the horses. They are dressed like pony boys and put into a harness. Mostly naked from the chest down apart from the harness and their tail which is a big butt plug. And then they race and they pull their alien mate around an arena on a carriage type device.
The winners of the race get cock peircings. The more races won, the more peircings you get around the cock. And as the males get more pregnant, and their stomachs expand, they still race right up until the day of the birth, though by this point they're normally in labour as they race and normally lose. The children, after birth are taken away somewhere unknown. They are never seen. And the humans are impregnanted again. A lot of the time, at pregnancy, it's more than one child inside. They come out as large rugby (american football) sized and shaped eggs, which later hatch.
I at least want this to start out as a kidnap rape kind of roleplay before turning into a man that respects his mate and loves him, in some way and wants to please him by winning the races, rather winning out of fear.
This is just a basic idea that I've come up with. More can be added. I'd love to hear others thoughts so shoot me a PM to discuss more, and the alien race can be more developed by you. They can be whatever, tentacles, multiple cocks, big ones, whatever you want.
Though I am looking to play the human boy here, not the alien race one.
Send me a PM if interested :)