Sam and Bobby

Sam Winchester and Bobby Singer have working relationship as well as a friendship. Like Sam, Bobby is a hunter. Bobby is also a father figure for Sam and Dean. Although Sam isn't Bobby's favourite, they do get along well and help each other. Bobby does say that Sam is a better hunter though.

Background
Bobby is a family friend of the Winchesters, so he has known Sam seen he was young. Around christmas time, Bobby gives Sam a necklace to give to John. This necklace later goes to Dean. Also, when Sam was young, refered to Bobby as "Uncle Bobby" (correct this if wrong). Sam later runs into Bobby in season 1's Devil's Trap. Bobby helps the boys get ready to rescue their father. Sam doesn't see Bobby again until much later.