In Of Mice and Men, Lennie doesn't want to fight Curley because he's afraid he'll get in trouble with George.
Lennie isn't a fighter anyway, and never wants to cause trouble. So he isn't inclined to want to fight. But he is terrified of fighting because he thinks George won't let him tend the rabbits on their imaginary farm if he gets in trouble.
Once he does understand that George says it's okay if he does fight back, he quickly catches Curley's fist in his hand and smashes Curley's fist--fight over.
Curley's fist was swinging when Lennie reached for it. The next minute Curley was flopping like a fish on a line, and his closed fist was lost in Lennie's big hand. George ran down the room, "Leggo of him, Lennie, Let go."