I'm planning to write an "adaptation-type" crossover as a one-shot, possibly continued if anyone likes the idea and wants to see it continue from there, but all I have set in stone besides the physical actions (what happens) is that it's meant to be an AU from Mara's POV with Luke and Vader set between ANH and ROTJ (when exactly is undetermined), with the point of divergence being in the fic itself. In addition, while I've read many a fic involving these three characters, I'm not sure that I have them down pat, or at least not to an extent that I would be able to write them recognizably. Mara and Vader would both be publicly visible (the former in "official cover," i.e. as an Imperial Palace dancer, the latter in "Darth Vader cover" *cough*), but in terms of what they would say, or how they would word their thoughts in reacting to sensing something amiss, I don't know the words or language... I did just think of having Vader actually be silent throughout the fic, but then I'm left wondering how to write him reacting (from someone else's POV) to a disturbance in the Force in the same room... much less how Mara would do so.