To be honest, I'm not sure what the story is for the other races. I like to think of the lizardmen as a mysterious clan that even the orc leaders don't understand, but they are both on the margins of civilization and so cooperate.
Generally, I wouldn't see the orc/goblin relationships as enslavement, but only because they don't codify things as such. The smaller ones are pushed around and told what to do, they can either obey, get whacked around, leave and be killed by the humans/elves/dwarves who are distrustful of them, or find someone they can bully to do their job.
Witht the Ogres, they're probably tricked into doing what the orcs want even when they try to bully the orcs.
Of the options availible in game, I think they would probably go for leaves or AV, because those put the least constraints on their behavior. I would think civs don't adopt OO unless they go near the ocean and get contacted by the creepy things in there. The Orc leaders might try to bring in Runes or Empyrean to civilize their clan, but that would certainly be an uphill battle. And I can see them becoming embittered if they fall behind thriving human civilizations and embracing a nihilistic Ashen veil sect.
I had a story in mind where an old Jonas would do just that, encourage the worship of agares for destructions sake, and Sheelba would seek help from the Bannor to purge it from their lands, knowing the incursion of the Order would be harsh but not wanting her people to bring their own destruction upon their selves. "Dying Embers"
