PCs are the heroes of the game world. By definition, they're the good guys!

Well, at least the guys the players are cheering for, anyway.

Intra-party conflict is nothing new, though. After all, would your thief be truly worthy of that title if he didn't occasionally attempt to pick the pockets of his compatriots? However it's rare that it escalates into actual fighting between PCs. Maybe if you catch that stinking thief you should just whip out your sword and teach him a lesson...

Transcript

Padmé: Oh cool. This is awesome. Sith Lady and Sith Lord ruling the Galaxy together!
R2-D2: And Sith Droid.
Obi-Wan: You're deluded, Anakin!
[SFX]: Whooom!
Obi-Wan: Your ambition has blinded you to your corruption. Any rule of terror you begin will be destined to fail.
Yoda: Go Obi-Wan! Stop him!
Obi-Wan: Oh, you're on my side now? I thought I was all alone in this.
Yoda: I was wrong! Anakin is totally the bad guy!
R2-D2: It's unnatural seeing two PCs fight one another. On the other hand, if one of you has to die, it should be Ben.
Obi-Wan: Your vote of confidence in the side of Good is overwhelming.
[SFX]: Whooom!
[SFX]: Leap! {Obi-Wan jumps from the floating wreckage on to the bank of the lava river}
[SFX]: Somersault!
Yoda: I vote twice! Go Obi-Wan!
GM: Is any of this in character?
Padmé: Oh... sorry.
Padmé: I turn a slightly deeper shade of blue.