George is the small intelligent man, the protector. He has a huge heart, but doesn't want other men to see his heart as weakness. He loves Lennie and takes care of him. He feels obligated to do this, but he is not bitter for it. Years ago, he used to make jokes at Lennie's expense, to try to get other men to like him. But now he just protects him. George ends up shooting Lennie to protect him, in a way. He puts him down, like an animal that has done the wrong thing. Like a pet that he loves, that he doesn't want to see suffer any more pain. I can't imagine making such a choice. My husband asked me recent, "What would it take you to kill?" I couldn't answer then. But now, I think that I could only kill to protect someone else.
Slim is a kindred spirit with George. He has earned respect in a different way, so doesn't have to hide himself as much as George does. But he sees who George is almost straight away. He also sees what Lennie is, and the understands the real reason why George looks after Lennie. He understands that George didn't shoot Lennie in self-defence, but as an act of kindness.
Curley's wife cannot be blamed for Lennie's death. She couldn't have known how Lennie would react. She was playing with him, with a slightly cruelty. She was also lonely, and used her sexuality to get attention because she didn't know any other way. If she hadn't screamed, she may have survived. If she was smart enough to realise that Lennie wasn't trying to hurt her, and calmed him down, she may have survived.
Carlson is a stupid man that reacts emotionally, and tries to please whomever he sees as the alpha male in the situation. He is not sensitive, and has no insight into other people.
The title refers to the small men, and the real men. It divides men between those who are thugs, and those who are protectors of others. It divides men by their behaviour.
I think George did the right thing. He could have walked away, and not lead the men to Lennie. Lennie would have starved, or sought George out which would have been dangerous for George. He could have let the men catch Lennie, hoping that they would listen to Slim and hand him over to the police. Lennie would have been hung or sent to the electric chair, but his death would have been humane compared to the death that Curley would have dealt. It was unlikely, though, since Curley and Carlson both had bloodlust. George did the best thing in a horrible circumstance.