~Ravenpuff

Maybe some Twilight Sparkle exploring kinktober?

Ponies are always fun, especially solo Celestia stuff

Though also nice would be Glamrock Chica, maybe with some food-based prostitution

Or Mangle (especially the Foxglove/Roommates version) probably giving someone a "massage" or other tension relief.

All that said, merfolk oviposition is something I don't think I've seen you do before and honestly pretty hot conceptually.

Idea 1, possibly easy: your MLP OC's Sunbeam and Bluebell, with either complementary or matching mutations. On second thought, that'll potentially be a rat's nest to figure out.

Idea 2, possibly hard: "There is No Game: Wrong Dimension" has two endings and barely a fanbase to speak of. Anyway, one of two endings has a two-headed flying squirrel as an incidental detail; the other has Tie, a flying squirrel warrior shown from the back in a still image (probably a squirrel, might only fly as a power). So: Tie, two-headed but otherwise your interpretation, kissing himself.

For idea 2, I suggest playing TiNG:WD, but that sounds like homework, and so does watching a complete playthrough. So here's a link to both endings (includes callbacks to basically everything): https://www.youtube.com/watch?v=-NTqmQniK7s