Vette is a mostly lightside character but Quinn, Peirce and Broonmark are all darkside.
Pierce and Broonmark both like a high body count, but Quinn is about strategy and loyalty to the Empire.
Khem Val is a weapon that does what you tell him. Speaking of companions warrior third one pushes it towards dark I would say.
ALL companions are weapons that do what you tell them. And Jaesa is whatever alignment the warrior decides to make her. She doesn't push the warrior either way.