George tells the boss that Lennie is his cousin, and tells Curley that they travel together.
The boss is suspicious of the relationship between Geroge and Lennie, because George speaks for Lennie. He wants to know if Lennie is incapable of talking or working, or if George is stealing his pay. He doesn’t know why anyone would “take so much trouble for another guy.” He wants to know why George protects Lennie.
George said, "He's my... cousin. I told his old lady I'd take care of him. He got kicked in the head by a horse when he was a kid. He's awright. Just ain't bright. But he can do anything you tell him." (ch 2)
The boss finally decides that you don’t have to have brains to work on a ranch, and lets it go. The men are not so lucky with the boss’s son, Curley. George knows immediately that he’s a troublemaker, and will try to pick a fight on a man Lennie’s size to prove he is tough.
Curley is annoyed when Lennie doesn’t respond to him, and says he needs to talk when spoken to. George gets protective.
"We travel together," said George coldly.
"Oh, so it's that way."
George was tense, and motionless. "Yeah, it's that way." (Ch 2)
George knows that most men won't understand why he and Lennie travel together, or the symbiotic relationship they have. George needs Lennie as much as Lennie needs George, because he needs companionship and someone to protect, just as much as Lennie neeeds someone to protect him. In the dog eat dog world of the migrant, this is an unusual situation.