I've got two unaffiliated characters, neither of which sounds really suited to what you're going for, but screw it.
Val Drutin is a "Dark Side Force User" in the sense that he was trained from childhood by a Sith lord. He has a decent array of Dark Side abilities, but his insanity and weird personality tempers the whole "evil knight" thing to the point where I'd say he pretty much is gray, maybe even leaning more towards the light. Having him in a group is counter to his character, though, since he's so unpredictable and hard to get along with. Maybe he'd join up with your guys on a whim for a little while, but I can't see him sticking around in the long term.
Alyosha Drutin is a character I have been trying to get involved in some kind of group, although his reasons for doing so are purely selfish. He has a bounty on his head at the moment and wants to find a crew willing to help him take down his former employer. Beyond that, all bets are off - he's a loner. He's also Force sensitive, but has had no training whatsoever - he barely even knows what the Force is. Unless we were to set up some plot thread where your guys took him on as an apprentice (which I can't see happening right now, because he is a depressed nerf herder who just wants to make money and kill people; he doesn't have the drive to devote himself to something like that), he doesn't fit the model at all.
Wonderful!