Both Castor, the black mamba naga, and Guest were born and raised in the demihuman zoo, but not together. You see, demihumans live in the enclosure with others of their species and Guest is not a naga. So, realistically, Guest and Castor never should have met, and yet...

Castor is an outcast because of his deadly venom. And Guest is also an outcast, but for different reasons. They understand each other. They talked. They bonded. And, eventually, became secret mates.

Now that Castor and Guest are mated, they still live in separate enclosures. They haven't told any of the staff about their relationship, mostly because Castor hates humans and doesn't trust the zookeepers. Unfortunately, they may no longer have a choice. Because Guest is pregnant and that is gonna become obvious eventually. Especially since no one in their enclosure seems to have any romantic interest in Guest.

Naga are part-human part-snake demihumans with the torso of a human and the lower half and tail of a snake. Nagas lay eggs. They can even make their non-naga mates lay eggs with half-naga half-other children.

Demihumans are part-human part-animal beings. In this world, demihumans live in demihuman zoos.

You can be whatever demihuman species or gender you want. I would just recommend you choose to be a merfolk or another ocean section demihuman. Check my Demihuman and Demihuman Zoo sourcebooks for demihuman species.