Since i am bit of Noob, i haven't really encountered a Trans-RP Character but i have encountered something similar when i was writing up a character for an RP i noticed a character that was refereed to as a Demigirl (not part of the rp my guy was rejected) and since then i have been thinking how much of an actual effect could a character gender have on the story, Because in the end factors like if your guy was a chick (Or was in relationship with a dude) at some point in the past these thing seem very trivial (Unless your in a Romance Focused RP) and i think the only way you could have these thing have any effect on the stories was if these things where the focus or that you would continuously bring up the fact in the RP (which could get on someone nerves)