mnchn, monsterfuck(?), maybe mpreg too (or eggpreg because fish lay eggs), mermaid chn and human mnh, chn can turn his tail into legs whenever he wants, since the beginning of the relationship mnh has always been curious about what it would be like to have sex with chn in his mermaid form, chn finds his curiosity amusing and invites him to try, but chn forgot that he was in the fertile period and they end up having a baby on the way or not ╮⁠(⁠＾⁠▽⁠＾⁠)⁠╭

(btw chn boypussy in mermaid and human form 🫠)