My bil is like this.
Everything is a drama in which he is the woebegotten victim.
He has it far worse than anyone else and no-one understands just how very very hard it all is for him.
When he's ill, he's iller than anyone else has ever been. Obviously. Even if it's just a bit of what is going round, he has it worse than any of us.
When he works, he's far more exhausted than anyone else ever gets. This is because he is the only person who has ever had a job....well ok, other people have jobs too, but their jobs are easy compared to his job, which is much harder than everybody else's. Anyone who says any different is a bastard and just doesn't understand.
When he is expected to get his finger out and behave like an adult, he has been treated far worse than anyone else has ever been treated and none of us have any idea what it's like to be such a poor wee lamb. It's not his fault after all...life has dealt him a very tough hand and he has it harder than all of us. This is something we must remember at all times, and any allusions anyone makes that life can be hard for all of us, has him apopleptic with fury. Because we don't understand.
The lazy self indulgent twat has lived with mil and her dh rent free, bill free, and responsibility free for 10 years.
They have finally decided he needs to move on and get his own place, as he has been mollycoddled enough now. He has not contributed a penny or an hour of his time in that decade. If he is not at work, he is too exhausted to lend a hand with anything, and prefers to lie in bed 'recovering' from having to go to work. 
Bil is now furious at his 'maltreatment' and is badmouthing his mum and her dh left, right and centre to anyone who will listen. He has been bullied, ignored and tossed out on his arse according to him.
His mother has bought him a nice flat to move into.
He is 40.
He has been treated very nicely and cared for very well by his mum and her dh, but bil cannot accept this and quietly go about getting the fuck out of their hair. He has to make a scene and cry DRAMA!
He has always been this way. I have no idea what is wrong with him.