I think it should be some guy with no records no one knows his name and the republic seem to be hiding something from him although he appears to have a connection to a dark lord or something like that either way i think that the game should not dwell on his past but on the future and the present we want some way of avoiding his past.
A good place to start the game would possibly be a crashed or crashing sith ship either way you need to escape. Shot down by Mandalorians?
But i think that the exile should already be dead because we did not see him get off Malachor V but this could mean we find him again as a dark or light Jedi.
Revan should be (if he is alive) on hoth or somewhere on the outer rim but hoth would be a good place.