It doesn't take science -- let alone Aperture Science -- to know that people can't be trusted. Thankfully, Cave Johnson and company built some robots, and then some "better robots," in an effort to overcome the unreliability of human companionship.

The result, Atlas and P-body, is the robotic duo best suited to overcome the perilous panels and heaps of deathtraps laid out in the Portal 2 co-op campaign. The only problem? They'll have to be controlled by you and a human "friend."