In the beginning of the novella, George and Slim talk about Lennie. In one of the rare moments in the book, George and Slim connect and have a real conversation. George shares with Slim his past with Lennie.
When Lennie's aunt Clara died, Lennie stuck with George. In time they became good friends. George also explains that Lennie is a great worker, but not too bright. As an example of this, George recounts a story of when he told Lennie to jump in a river. He actually did. The problem was that Lennie did not know how to swim. Therefore, he almost drowned. When George realized that Lennie would do anything he asked him to do, he stopped playing pranks on Lennie. George did not want to take advantage of Lennie. Here is the quote:
George’s voice was taking on the tone of confession. “Tell you what made me stop that. One day a bunch of guys was standin’ around up on the Sacramento River. I was feelin’ pretty smart. I turns to Lennie and says, ‘Jump in.’ An’ he jumps. Couldn’t swim a stroke. He damn near drowned before we could get him. An’ he was so damn nice to me for pullin’ him out. Clean forgot I told him to jump in. Well, I ain’t done nothing like that no more."
“He’s a nice fella,” said Slim. “Guy don’t need no sense to be a nice fella. Seems to me sometimes it jus’ works the other way around. Take a real smart guy and he ain’t hardly ever a nice fella.”