Hello! I've been back for, say, a week after a long hiatus, and I feel much better as a person, but more importantly, as a writer. I was going over my former RPs, though, and I found one I still quite like, and wish to do something similar again.
Beyond the reach of the Empire (because there's always an empire), barbaric tribes roamed and settled in the vast forests, mountains, and plains. Feared especially were a fierce, independent people who dared do what little had the nerve to attempt: they rode into battle on horsemen. They were archers, trained for accuracy, closing in with the powerful centaur, wielding spear to gore any who stood before them.
Our story, however, is of how one of the brave people of the tribe brought the horsemen to field. They did not originally come of their own accord. They are wild creatures, valuing their freedom, not apt to give it up. They must be beaten, they must respect, before allowing to be mounted. Once that has been achieved, though, a centaur's loyalty is absolute, and will serve until death.
You can attribute to the tribe whatever fantasy race you wish, or simply humans, as long as they're humanoid, and you can see them riding a centaur, as much as you can see anyone riding a centaur. I imagine this RP being a clash of two dominant people, however that manifests. Will your character be sneaky, luring the somewhat simple centaur into a trap? Will they somehow try and use diplomacy? Or will they be forward, and beat the centaur in personal combat? If they themselves are beaten, centaurs are rowdy creatures, and may take their defeated opponent as a prize, as they would expect no less if they themselves were defeated.
Do PM me if any of this strikes your fancy. We can talk about more specific details there, as there are different paths we can take. I'm tired as I write this, and will no doubt edit mistakes made tomorrow. I hope to hear from you soon, have a good night when the time comes, wherever you are.