I am currently GMing a small RT group with three players. I laid out the guidelines for the game and the characters before play began and allowed the players to discuss what they wanted. As a result, we have moderately experienced characters that began midway through Rank 3. The overall campaign theme was stated to be exploration of the unknown with a mix of social, combat, and investigation thrown in. It was stressed before character creation that flexible characters would be best - overspecialized characters would limit participation in certain activities. Two of the players took this to heart and created a flexible team of a Rogue Trader and Seneschal. They are not the problem...
The third player decided she wanted to play a Navigator - specifically because they are "so weird'. I suggested the Navis Scion in an effort to get her a bit more access to social options, but the player almost knee-jerked away from it. She instead made the least social Navigator possible, with numerous mutations (including Unnatural Presence) and Talents like Unnerving Voice. She also made a big show of describing (in lavish detail) her rainbow-colored hair and painted nails, her unicorn body tattoo, and numerous other eccentricities. She even loves to describe how her eyes constantly twitch - including her Warp Eye, which she doesn't like to cover. I pointed out that this was basically like waving around a loaded gun, and she thought that was "cool" and asked if it helped her with Intimidate...
Once play began, the problems kicked up. She insists on her character attending everything, and she's messed up several social scenes. Even worse, she undermines the other player's attempts in these social scenes by trying to Intimidate everyone. When the players softly express their displeasure, she begins having her character do outrageous stuff in an attempt to draw the spotlight back onto her and her character. In fact, anytime her character is not at the heart of a scene, we have to hear about her character's new tattoo or some such detail that's really only interesting to her. She also has the "bored now; I'll keep opening doors until I find something interesting/dangerous" that's almost gotten everyone killed. Lastly, she's taken to having her character threaten to strand the ship in the middle of nowhere if they don't let her have her way.
So, lots of problems here. If she were not the fiance of one of the other players, I'd likely just bump her from the game. Also, she's a fun person to associate with outside the game, but in-game I find myself tuning her out more and more often. With only three players, that gets pretty obvious quick, and can trip the "bored now" crap-tastrophe, making the matter worse. I'm now three sessions in and already irritated. I intend to talk with her and the rest of the group before the next session, but I'm looking for some input on what angles might be best to take.