Still need help for Bandit

Our aggressive cat Bandit seems to be doing better. We have been letting him out supervised to visit with the other cats and the only thing I've noticed is that Smokey is instigating the fights now. I'm not sure if it's because he's been the one let to roam free while his brother is locked up or not. If that's the case, we have a huge territorial issue now. Bandit doesn't seem to have the aggression that he did before, he will now sniff Smokey face to face and not have any issues with him, we are still not sure what triggered it before though. Now when we let him out Smokey will sniff him, be fine for awhile and then start biting Bandit's neck, which normally means he's showing dominance but Bandit was always the top cat before and the only thing that happens is they start to fight again and we have to put Bandit anyway. The reason why we have to put Bandit away and not the instigator is Bandit will re-direct his aggression towards us and Tiggs. For people reading this, I've posted two other threads about this issue, both cats are fighting to the death with each other after Bandit snapped out of the blue and attack his brother Smokey. Both cats are neutered and have been best buds from the time I got them which was 8 weeks old and they are now 4 yrs old. They have never been separated and this type of behavior is not normal for them. We took Bandit to the vet and we all thought there was something mentally wrong with him, he would spin and hiss at nothing in the carrier and have moments where he would just stare off into space. He attacked his brother to the point where he hurt him. We have noticed that Bandit is fine with his sister Tiggs, she was introduced just over a year ago and seems to be fitting in fine. I've read all the articles about aggression and re-introducing cats that fight, nothing seems to be working. The vet seems to be out of ideas and we have tried the Feliway diffuser. We don't live in an area where we have animal behaviorists either, please please help!