This is very likely not something that he help, no matter what you want to call it. Call it "dependent personality disorder with depressive features," if that makes you feel more charitable toward him. But don't set yourself up as judge of what anyone can, or cannot, help. It would take the omniscient mind of God to discern that. He is seeing things in the way that serves needs he has. Your mom is doing the same thing. Avoid demonizing one and making a hero of the other. Concentrate on the relationship you have with each of them. Don't try and mediate between them. How they treat each other is really their business. How that got to where it is involves things you don't understand.