1. New Male in the (Human) Pride/Marriage Gives you Access to Other Girls
I thought up these separately, but they are similar enough I am going to treat them as one.
In the pride case, humans live as prides. In this case a younger man has just come in and killed/chased off the older man. Afterwards he dealt with any sons of the previous man and now the women are all his. A groups that are mothers/daughters/sisters of each other, and they are now all his to mate with. Perhaps this is in a more primitive/tribalish society with them behaving like a pride in other fashions. In this version, the women may or may not have an instinctual desire to mate with him after he took over.
The other variation is probably modern and more social/legal. In this case, when a man marries, he is allowed and often expected to have sex with other women close to his wife. Her friends, coworkers, sisters, depending on ages potentially mother or daughters that had a different father. It is semi-free use, the man can casually fuck them when he wants. He is not expected to have close relationships with them, but is almost expected to have sex with them with some regularity. Of course this means many women have several men at a time potentially, their own husband and husbands of women around them.
I suspect I would be playing the boy here, and you would play one or ideally more of the girls. Similar to my last bulletin, being willing to play through impregnation/pregnancy would be a big plus.
2. The Last Magical Girl Trains a New Generation (potentially MxF and/or FxF)
I had previously posted this in the Public RPs club, but since it was not getting attention, I decided to past it here. If I wasn't at max clubs, I might have made it a separate club. This one is likely to have a heavier story but still plenty of sex mixed in.
I'm thinking anime style 'magical girls' here. In the past many threats to humanity were dealt with by such girls. Sometimes the larger population was aware, many times they were not. The previous threat was ultimately defeated but at great cost. There was only one survivor (picture for her appearance, and the character I would play, yeah she looks more like a wizard than an anime magical girl, but we can figure that out).
She had not been the leader previously. She was merely the last one standing, with the help of damage her comrades already did, last minute assistance from their spirits as they died, and using all her power, she managed to defeat the enemy but was mentally and emotionally drained and scarred. It was her hope that they ended the threats that would require magical girls for the foreseeable future. For at least a few years, this seemed to be the case. Eventually she foresaw a new threat though.
By herself, maybe, she could have dealt with what was coming but sooner or later a new generation would be needed to take over. So now she seeks out one and eventually more apprentices. We would begin with you playing the first apprentice and I (we if you want) could play various other side characters, which could be a mix of male and female. The focus is on the older magical and her first appearance and the bond developed between them, mentor/student, very likely lust, possibly love. One or both could get involved with other girls or men too and they could include people around them, or the enemy. We can discuss the details, I have more of a vague overview in mind and open to suggestions on the details.