In Chapter 1, George says,
"Guys like us, that work on ranches...work up a stake and then they go inta town and blow their stake...they ain't got nothin' to look ahead to...with us it ain't like that. We got a future".
They must act with responsibility, differently from those who have no future.
Lenny responds with a comment on friendship and the responsibility that goes with it, saying,
"Because...I got you to look after me, and you got me to look after you, and that's why".
A little later in the same Chapter, George has hurt Lennie's feelings and tries to rectify it with understanding, telling him,
"I ain't takin' it away jus' for meanness...that mouse ain't fresh...you get another mouse that's fresh and I'll let you keep it awhile".
Then, Lennie realizes he's annoying George with his demands for ketchup. He tries to be understanding and says,
"I was ony foolin', George...I wouldn't eat no ketchup if it was right here beside me...I'd leave it all for you".
In Chapter 3, George admits with honesty he used to treat Lenny badly. He says,
"Used to play jokes on 'im 'cause he was too dumb to take care of 'imself...he was so nice to me...I ain't done nothing like that no more".
And finally, in Chapter 6, after he has killed Curley's wife, Lennie tells George honestly,
"I done another bad thing".
Wow thank you so much dymatsouka
you really helped me out :)