Popular opinion: Lennie is really stupid and dumb. He is retarded!!
Internal Conflict: George's feelings about his friendship with Lennie. On one hand, he loves the big man and seeks to be his protector and caretaker from a society that has little patience with people that has mental disability. But, on the other hand, George wants to be free of his responsabilities. He frequently comments that live would be good without Lennie.
Lennie vs. Curley: As soon as George and Lennie arrive on the ranch, it is apparent to George that keeping Lennie out of trouble will be a constant struggle, creating immediate conflict in the story. The boss's son, Curley, wants to pick a fight with Lennie the moment he lays eyes on him due to Lennie's tall stature. Curley is an amateur boxer, but Lennie is so strong that George worries about what could happen if that strength were to be unleashed
Man vs Society: Lennie suffers a lot because he has a mental disability and some people take advantage of that. Lennie has a heart ,he is not an animal and those kind of things hurt too. No one completely tolerates lennie and he struggles sometimes to fit in.