Bump with an idea to get things started.
Seeing as I'm hoping to mix things up with a yuri arranged marriage, I had to think up something to justify this. :3
The idea is of course, that the arranged marriage is set between two kingdoms perhaps as a peace treaty or whatever other reason we come up with. Things is, it is set between a young prince and a young princess. So, they have the marriage ceremony, and I'm thinking the princess would be especially thrilled to marry such a handsome young man, but eventually, she would find out the man she had be admiring was actually a young woman like herself. The prince would have been born a girl, though she would be raised as a young man and shown as a prince in public and so on.
So then it becomes an issue of whether or not our princess still feels the same about her 'prince', and if the secret of the prince's identity is revealed, there could be chaos.
Just tossing some ideas around. :3