I have a fic rec for your first request! Blackbird Claw, Raven Wing by Violsva is one of my very favorite f/f political/arranged marriage fics, where the usurping king has disposed of his sister by marrying her off to a knight and sending them both away to the knight's ancestral home. I really love the slow-burn relationship and the mix of melancholy and hope in it.

I remember reading a second one that seems even more up your alley, but I can't seem to find it. If I do, I will come back with a link. :)