"Curley's fist was swimming 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." Curley acted mean and thought he was above everyone. He got what was coming to him.
"and her body flopped like a fish. And then she was still, for Lennie had broken her neck." Curley's wife was very mean to some of the characters, including slim. She got what she deserved. What comes around goes around.
"And George raised the gun and steadied it, and he brought the muzzle of it close to the back of Lennie's head. The hand shook violently, but his face set and his hand steadied. He pulled the trigger." Lennie caused much trouble for himself and others. The chaos he can cause is over. He lays at peace now. A confused man in a horrable world.