Quote 1
Crooks scowled, but Lennie's disarming smile defeated him. "Come on in and set a while," Crooks said. "'Long as you won't get out and leave me alone, you might as well set down." His tone was a little more friendly. (4.22)
Crooks has been lonely and friendless for so long that he almost can't deal with someone trying to be nice to him. Psst, Crooks: you win more friends with honey. Or something like that.
Quote 2
"George can tell you screwy things, and it don't matter It's just the talking. It's just bein' with another guy. That's all." (4.39-40)
You know how you have those hour-long phone conversations with your best friend about absolutely nothing? (No? text chains then, or however kids communicate these days.) That's what Crooks is talking about. It doesn't matter what you're talking about—just that you're making a connection.
Quote 3
Lennie smiled helplessly in an attempt to make friends.
Crooks said sharply, "You got no right to come in my room. This here's my room. Nobody got any right in here but me." (4.7-8)
It's hard to pick the most sympathetic character in Of Mice and Men, but Crooks comes close. Isolated because of his skin color, he's been alone for so long he doesn't even want to make a friend.