Star Wars: Rogue One Trailer 2 - 14 Major Plot Clues
9. K-2SO Is C-3PO On Steroids
The former Imperial Battle Droid, K-2SO is bound to be used as both a powerful mirror on humanity and comic relief in Rogue One, and it's already hard not to see him as a stand-in for C-3PO.
There's obviously a slightly different dynamic here, because he used to be a murder-bot rather than a Protocol droid, but he has the same sort of affected mannerisms and speech quirks. It's almost as if he has a Protocol's OS within his hulking frame.
Perhaps that's how he was reconditioned?
He's also this movie's C-3PO in the sense that he flaps about impending danger: though he doesn't quite screech about doom, his warnings are very like Threepio.