Semi related to the recently asked questions about non human pregnancy and impregnation scenarios:
An inhuman symbiote needs a host to survive, and a human womb makes an excellent home. This gives a cute perma belly. But when they go into heat the host needs to find another member of their species to crawl inside with them and let them mate together and lay eggs inside their safe environment in the host (bonus if the symbiote species are hermaphrodites).
Now, the way this ends after the eggs are laid for incubation is the mate could exit again or the symbiote settled in the host eats them. Ultimately, the eggs are going to hatch in there and the host will have to push out the live young.
Oh, this is a clever idea. It works really well, whether the host is a willing carrier or not.
You've got the initial implantation of the symbiote, followed by the need for a second symbiote to crawl into the host's womb to reproduce. The host may or may not notice the symbiotes mating and/or one of them potentially eating the other. Then the host is filled with eggs that grow and hatch, before the host gives birth to the resulting offspring. All these things lead to lots of delicious opportunities for growth, movement, sexual stimulation, and the process of giving birth.
Love the way your mind works for this scenario!
(Replies for Mayternity's "If you could be 'pregnant' with anything non-human, what would you choose to carry?" and "What's your favorite impregnation scenario?")