Of Mice and Men Part One

As far as I can tell Lennie is dependent on George because he has a mental disability.  That or he was simply never taught anything but how to talk, so he doesn't know how to survive on his own.  I think it is the first one, that he is mentally disabled.  Either way he does not have the skills or the knowledge to care of or provide for himself.

I think that George keeps Lennie around because he feels sorry for him.  I think he realizes that Lennie could not survive on his own, and so took him with him.  Either that or the more likely case is the Lennie is George's brother.  He probably realized that if he left his brother he would not be able to survive and would probably end up in jail or as a homeless person begging for money and living on the side of the street.