What kind of relationship do George and Lennie have? Why?

George and Lennie have a close relationship; it's almost like a father/son relationship. George being dad and Lennie the errant son. I don't think their relationship changes much in the story, outside of the fact that in the end George makes the decision to let Lennie go and decides that to do it himself is more humane and a greater expression of love. He is consistantly frustrated by Lennie getting into trouble, but he does love him. George is a commendable man............. actually one of the best. George initially took on Lennie's care after Aunt Clara (Lennie's aunt) died, she asked George to care for him after her death.