As the ever expanding territory of the Therians started bumping up against other city states, tensions started to build. The spark that started the war was actually an accident. A Magitek head researcher had run out of places to store his chemical waste, and holding tanks are relatively difficult to produce these days. So instead he looked around for a different solution and discovered a pre apocalypse war waste pipe. Once he determined that wherever it went was quite some distance away from the city, he dumped the waste into it without giving it much thought. Where it went was to an old stormwater runoff retention basin that a Therian tribe had converted into a healthy and lush lake with a village built up around it. The results the pipe unleashed upon them were horrifying. The few terribly injured survivors traveled to other tribes, often with dead loved ones in their arms, and begged for vengeance for their destroyed families against what they assumed was a deliberate attempt to obliterate their tribe in order to claim their land for exploitation. Word spread, and one day a mighty hoard descended on the entirely oblivious Magitek city. Mercy was in short order that day. As defenders deep in the city tried to hole up to survive, a number of people escaped in airships and contacted non-Therian cultures begging for help against the onslaught and calling up favors owed and alliances made. As those groups started attacking the Therian hoard, other tribes of Therians joined to help their fellows. This process spiraled out of control and eventually most of the planet was involved. Ultimately the Therians were defeated and negotiations started. In time people got to the bottom of what had actually happened. While an uneasy peace took hold around the world, that could not erase the anger of those who had lost loved ones in the conflict.
There was also the question of what to do with all the Therian prisoners of war, which in some cases included all survivors from a tribe. Many were consumed by rage and a lust for vengeance against those that had killed their loved ones and families, others were filled with sorrow or psychologically broken from the terrors of war or their losses. While it wasn’t always clear who had done what, it was known that many of the prisoners had racked up kills of their own and not always just against enemy soldiers, so many cultures felt justice demanded they not simply be set free. However keeping angry Therians with their magic and biomorphs in prison was deadly and costly. In the end magic collars were developed. They essentially enslaved the individual by suppressing their memories from before they were collared, filling them with calm, and giving them a predisposition to follow orders. It was claimed this was a mercy for such traumatized individuals, or at the least much more humane and enlightened than giving them “what they deserved”.
While the Therians continue to heal more lands, they are upset about some lands that were stolen from them during the war, and about their fellows still held in collars. Tensions are rising again, and this is what led to the creation of the school where the game takes place.
In game, characters from certain cultures could have collared Therians in their control, or would at least have some in their tower. As always, these represent generalizations as opposed to rules.
Bushido culture: They have taken responsibility for most of the Therians that they had captured, and more or less treat them like their paid servants from their conquered cities. As collared Therians are calm, follow orders, and are not predisposed to speaking unless spoken to, the Bushi actually tend to prefir them.
Celestial culture: The celestials felt a responsibility to keep Therians from falling into abusive hands, but are too fearful of what might happen if the collars were removed, so many collared Therians are found in Celestial cities. This is very awkward for the celestials who oppose slavery and if anything treat the collared Therians better than a typical celestial. Therians are still expected to “put in honest work,” but the celestial giving them orders usually appears quite emberassed.
Magitek Culture: The Tech Mages don’t have slaves as such, however they often have minions whom they can be rather absent minded about in terms of payments and such. The collared Therians generally just blended in with the other minions and at least get fed well enough for their labors.
Netherkin culture: Netherkin are highly variable, but some have certain cruel needs in order to continue their existance. Those were more likely to have gotten involved in the war, and may have relished the opportunity to gain some thralls.
Pactmaker culture: This culture already had the concept of indentured servitude, and so individuals gladly took “responsibility” for as many collared Therians as they could. They treat them as slaves, but “rationally” in that they generally seek to keep them in good health and decent spirits.
Therian culture: The Therians largely stayed on the same side of the conflict and would free their collared fellows if they could.
Wanderlust culture: This culture doesn’t keep any collared Therians (or much of anything).
EDIT to self:
Consider pointing out that children may be tempted away by the big cities of other cultures, Therians may gain people in part because the transformation can help in creating a new life for someone that wants to leave their past behind and get a fresh start.
Consider 30 pts of biomorphs (no single one over 20 points) and 10 points of bio-magic, giving them more room to grow and less of a "magic" aspect they may not like.
Perhaps shift emphasis to transhumanism, and their exploration therof.