Am I my Brothers Keeper?

I've been thinking about my brother a lot lately, mainly because he keeps calling. He wants me to visit him, for some unknown reason he can't visit me.
I don't like visiting him. He is eight years my senior and is reckless and unaware of the feelings of others. His addiction is to marijuana although I'm sure he's on stronger things as well - his excuse, he can't stand the pain, life is pain damn it, we don't all turn to drugs. He takes no responsibility for his actions, and boasts about abusing children in his past. The rest of my family have more or less given up on him. I know he is beyond help, he says he wants help, but he wont put the effort in. I've given up trying to help him, but I wont give up on him, I can't leave him with no one.
He's gullible, at times almost infantile, I feel sorry for him, I know I shouldn't pity him, it wont help him and he certainly doesn't deserve it. I've forgiven him for all the wrongs he caused me, but to hear him brag to others about it, I don't know whether to hate him or wonder about his mental state. Bragging about cruelty will not get him a girlfriend, sometimes I wonder how his mind functions at all. I understand he went through hardships as a child, but surely it's time to grow up and be a man, time to stop relying on the rest of the world to save you everytime you fuck up.
I am an independent person, I don't like relying on others because they will let you down, my brother, he is dependent on everyone. I don't think I'd mind visiting him so much if he didn't lie through his teeth every time he saw me. I'm good at reading people so naturally I'd notice, but he's so bad at it that everyone notices, how anyone could live with him is beyond me. If you could get past the lies the drugs would get to you, for at least six hours a day he pulls cones. I'm not a fan of narcotics, I've had too many friends die with a needle in the arm.
I love him, if only because I feel morally bound. I know that sounds bad, but I'm the only one that still does that for him, so it's better than nothing.