"Blubberin' like a baby! Jesus Christ! A big guy like you."
"Strong like a bull."
"George." "Make'um let me alone, George."
George holds power over Lennie. He controls everything Lennie does or says. He can't do anything about it or stand up for himself without George getting mad. He feels powerless because he can't keep something that keeps him calm without it getting it taken away. Lennie can't control what George is going to do or say.
Lennie tends to repeat things that George says if he likes them. George told Lennie that he was not allowed to talk when they met the boss. He didn't realize that he repeated George until he saw that he was mad at him. He then made himself quite and felt upset because he made George angry and he couldn't have stopped himself from speaking.
There is nothing Lennie can do to protect himself because he doesn't know how to. He's too scared to move from where he is because of the situation he is in. Lennie is powerless in this situation because he was put in a position that he doesn't know how to react in. Neither him or George could've assumed that this was going to happen.