First, consider Chloe Frazer.  She and hero Nathan Drake have a flirty romantic bond, yet she'll betray him temporarily if doing so will further her own agenda or covertly aid Drake (even if that means shooting him).  She has no issues with doing the dirty work if it helps her cause, yet in the end she turns out to be a trusted ally despite the fact that she's not really much of a team player.  Fans of the later years of television's Stargate SG-1 may recognize those character traits as describing Vala Mal Doran (also portrayed by Claudia Black), a sassy character with a maverick streak who flipped allegiances from time to time for the eventual greater good.

Then we come to Schäfer, the Nazi who was once part of an expedition to recover the Uncharted 2 MacGuffin, the Cintamani Stone.  After he realized what recovering the powerful artifact would mean to the fate of the free world, he turned against his team members, killed them, and sought refuge with friendly locals in a nearby village.  Now change gears to Star Trek: Deep Space Nine, where the Changeling Odo (also portrayed by René Auberjonois) turned against his own kind when he learned of their plans for galactic domination and instead settled with the friendly Bajoran/Federation crew on the eponymous space station.

It should be little wonder as to why both actors brought so much energy to their performances in Uncharted 2.  Both had played similar characters for years in other sci-fi/action franchises.  Say what you will about typecasting, but this game is better for it.