I'm currently trying to join an RT game wherein neither the DM nor most of the players are big fans of the 40k universe. Most of the time they poke holes in the way the governments handle things, or just how stupid most of the armies are. Despite all of that they're trying the RT version of the system if only to get a feel for the core of it, as the DM has expressed an interest in running it for a larger game.
Either way, the DM decided to leave if I can bring a Sister of Battle into the group up to the player playing the Rogue Trader. Problem is the Rogue Trader is wary of me being a Sister of Battle, as he's not exactly keen on going full "FOR DE EMPRAH!" and is likely to be a little heretical/radical. He's worried that a Sister of Battle would turn into a big debacle and I'd end up trying to kill his character. Thus he has stated:
"As long as this doesn't get retarded. And you come up with a good justification of it that doesn't start it off in conflict."
So thus my problem. I can't think of any good reasons as to why a single Sister of Battle would be in the service of a Rogue Trader. Think y'all can help?