How does friendship play a role in many of the dramatic events in the novel?

In chapter one we realise pretty quickly that Lennie has some mentally challenged issues. Well okay, he has allot of mental issues. When we meet George and Lennie he is crying about his dead mouse being confiscated. Apparently Lennie petted it to death. George obviously looks out for Lennie. Much like a six year old would be dependent on his parents, Lennie is completely dependent on George for everything. Throughout this novel there is a sense of loneliness and isolation among these itinerant workers. For all the trouble Lennie causes George, Lennie is still a faithful friend and confidant. True friendship was a rare thing to find in this context. Lennie and George truly loved each other. We quickly get sense that George's speech about their little dream farm was not solely for Lennie's benefit. The dream was shared by two men who were the only family to each other. Unfortunately George's must help Lennie one more time at the end of the book: he must kill Lennie before Curley and the other men hunt him down.