First, Uncle Joe is a Super Mutant. Second, he is friendly, unless if you attack him. When I found him he was being attacked by 2 vicious dogs, so be prepared to fight just in case. Uncle Joe is unarmed, so depends on the character for how hard of a fight he'd be if you wanted to attack him. Talk to him, and you'll have a few dialogue choices. If you ask him how he got his name, he'll tell ya that he thinks that was his name before he became a Super Mutant, or he read it in a book. Either way he can't remember.
You can also talk to him about his Super Mutant life, and learn that the Super Mutants are born this way. But created! He'll say that he didn't like that his brothers took captives to try and make more of them. He tried to convice them to stop, but they tried to kill him so he ran.
Continue talking to Uncle Joe and he'll give you something. I gotten a grimy pre-war business wear, but I'm not sure whether if it depends on level. You can find Uncle Joe wandering the Wastes.
Added by: wolflord755 Jul 2nd 2011, ID#7440