In a game a while ago there was a FtM prince turned hosteller. Left court and royal duties due to disillusioned and wanting to do actual good. But then they were a PC and quickly needed some help from granddaddy the king. I wondered what the king wanted in exchange. And it was clear - the royal line continued. In other words get an heir.
I checked with the player that this was an OK path comfort and safety wise. Afterall one way to solve it was for the prince to get pregnant, force upon themselves a gender they did not want etc. We talked about it and had regular checkins.
The moment that made this an awesome world building moment was when I realized magic impregnation wasn't an impossibility. Nor pregnancies without the biological bits. Because Magic!
Unfortunately we never to to that part before scheduling did its thing.