Forbidden Hybrids
Almost every species can make babies with almost every other species, so it's quicker to list the caveats and edge cases than to list every single possible hybrid. This doesn't mean that these forbidden hybrids can't happen at all, however! It just requires very extreme / unique circumstances.
Assume both / all parents are purebreds. If any parent is a hybrid it gets waaaaaaay more complicated.
- Divine races can't have kids with other divine races. Something about all that magic fries any potential kid.
- Archons can't have kids at all unless the number of living archons is below 729 because anything + archon = archon.
- Florafolk collect genetic material from several different people before producing a clutch of eggs, so unless the only two parents involved is the florafolk laying the eggs and one non-florafolk parent, 50/50 hybrids don't happen.
- There are no records of starchildren having kids of their own. Whether this is because they're infertile, the powers don't get passed down so the kid doesn't "count", or some other third thing is unclear.
- While a standard une'mea can produce children with whoever and whatever they choose, aquatic une'mea are known to have difficult pregnancies when the other parent is anything that's not another aquatic une'mea. Hybrid pregnancies carry a higher risk of complications and miscarriages, even if the other parent is a standard une'mea, and aquatic une'mea cannot have children with divine races at all.
- Vampires can technically have hybrids, but there's a catch!
- If left alone, the hybrid will start losing their vampiric traits when puberty kicks in, so when they're grown they look and act like a normal member of the other species.
- But if made to take part in "The Rite of the Last King" at any point, they go into a torpor-like state soon after and all their non-vampire traits will rot and fall off. If they survive they'll wake up a fully-fledged vampire.