He is the alternate reality version of Sam Winchester.
Growing up, Sam and Dean were spoiled by their father who came to lead the organization known as HunterCorp. Sam and Dean hunted monsters across their world aided by their own plane and being paid for their work.
In Destiny's Child, the alternate Sam and Dean arrive through the rift in the Men of Letters bunker in the Main Universe. However, due to the destruction of their world, the rift malfunctions and pulls them back in. Sam and Dean become trapped between worlds, visible as ghostly projections on the wall of the bunker, but unable to see their counterparts or Castiel.
Later, Dean suggests using their counterparts to trick God in case he comes to check on them. Sam uses a variation of the ritual from the Demon Tablet to bring the alternate Winchesters into the Main Universe where the two sets of Sams and Deans are shocked by the lives the other has led and the differences between their worlds. Sam and Dean explain that God is planning to destroy their world too, but they intend to stop him and need their counterparts help. The alternate Sam is shocked to learn that God checks in on them and Dean explains that they have a sort of relationship and they need their counterparts to pose as them in case God does check in. The alternate Sam is shocked and affronted when Sam tells him that he will need to lose his man bun and refuses.
While the Winchesters, Castiel and Jack are gone, the alternate Sam and Dean follow the plan set out for them, sitting around drinking beer in the Main Universe Sam and Dean's clothes though alternate Sam refuses to get rid of the man bun, feeling that keeping it is a compromise for being forced to wear flannel. While alternate Sam enjoys kitten videos, alternate Dean finds and enjoys Dean's porn. Though the alternate Sam is disgusted, the alternate Dean envies their counterparts lives which, while simpler, includes a place of their own, no quarterly reports and no investor calls, leaving them only to hunt monsters, drink beer and watch porn. The alternate Sam agrees with his brother, realizing that Dean is right about how much better their counterparts simpler life is.
After returning to the bunker, Dean sends the alternate Sam and Dean off to new lives in Brazil, rejecting their offer to live together like a club. Dean tells them that Brazil is perfect for them: a place where the alternate Sam and Dean can enjoy a simple life away from hunting. To Dean's anger, the alternate Sam and Dean reveal that they found and drove the Impala before quickly leaving.
Due to his upbringing, this Sam is more uptight about the rules than his Main Universe counterpart and less willing to adapt. To this end, he refused to even change his hairstyle to fit in. However, after seeing the freedoms their counterparts had, he became more relaxed and even enjoyed taking the Impala out for a joyride. He also didn't like alcohol much. He was shocked to learn that their counterparts didn't get paid for their work and managed hunting without their own personal plane. Sam was obsessed with his man bun hair, refusing to get rid of it and calling it "sacred." However, Sam comes to envy their counterparts simpler lifestyle and appears to have enjoyed going for a joyride in the Impala.