I'll put this right out there since I don't want anyone to get upset: Spoilers ahead for the current season of Game of Thrones. There will be tidbits throughout this that will spoil things going on this season. Read ahead at your own risk!
I would absolutely love to play a Khal against Dany in something filthy. Maybe he proves his worth by surviving the fire. Maybe he has taken her as his own 'whore' instead of bringing her back to the main city of their people. Up for playing this man as a slave owner near Meereen as well if you'd rather him be more 'civilized' but still taking what he wants from her.
Aside from that, I would love to write a guard against Cersei. One that she trusts more then anyone else and allows him to share her bedchamber because of it. He can let her take control or take it himself depending on how you would like to play her. This can also work with the Queen Margaery as well.
I would also be open to talk about lines with Arya, Sansa, Shae and a few of the other women as well so feel free to suggest just about anything if you would like to plot and jump in to something fun and filthy.