K-2SO just isn't quite like the other droids in the Star Wars universe. Give old C-3PO your backpack and he'll gladly carry it without much fuss (he might make a whiny comment or two before obeying). Tell R2-D2 to go open a door for you and he'll chirp a few cheery beeps as he nonchalantly rolls over to the door. K-2SO is more likely to drop your backpack on the side of the road, because he doesn't feel like carrying it. If you ask K-2SO to open a door for you, he'll tell you to open it yourself. But then, why shouldn't he be rebellious? He's a part of the Rebel Alliance these days!