any you'd like :)
for some good pic inspiration I suggest looking up "the monster girl encyclopedia" but since this section is non-adult roleplaying, you might wanna disregard the descriptive texts of each one, but keep their disposition.
I have some plots, these are the outlines of a few of them.
1: In the modern age, the world is different, since the end of WW2 where the Nazis used foul magics to try and defeat their enemies, they instead reduced the male population and changed the female population into monsters of all shapes and sizes, since then global society has changed, some places have gone completely baron of human life as the men killed the transformed women and later found that all women had become monsters, in other areas men and women live seperately, the women live in the wilderness, surrendered to their monster side, men are sent as a rite of passage to procure a bride, by going into the wilderness, and capturing a woman (who then imprints on them) and bring them into civilization as their wife.
I play as a young man, and his time has come to go into the wilderness and find a woman, and just pray he doesn't become captured himself and become a plaything for them like so many men before him, and you obviously play as either the first monster-girl he comes across, or as a group.
2: in a fantasy world, a succubus with god-like powers has dethroned the previous demon lord and put herself on the throne instead. This action has turned all man-eating monsters into... well "man eating" in other ways, now instead of raiding villages, killing children who wander into the Forrest, the monsters instead raid villages to capture "husbands" for themselves, and often kill their wives if already married, and instead of killing children who wander into the forrest, they instead work to implant positive sentiment with the little boys who go there, in the hopes they will return of their own accord, but all children born of a human and monster union will always be monsters, and so they remain an existential threat to humanity.
I play as a young guard to a medium sized medieval village, one night the village is attacked, you can decide whether he is captured or they manage to fend off the monsters, but one remains behind, wounded, and he takes pity on her.
3: My character is already in a relationship with yours, but a certain "kink" is thrown into their lives when your character earns the scorn of a powerful witch who we both think is just a crazy old woman, she casts a spell on your character and we both think it's nothing... that is, until the next morning, where our characters wake up to find yours has been transformed! and the witch is no longer where she was living before!