cranky duck

[didak]

I have 3 muscovy drakes, two of which are great friends but one of these ducks picks on the third one. After awhile I just had to keep the two permanently separated from him. This duck used to be quite a friendly duck and used to follow me around and sit outside the back door waiting for me etc. A month or so ago he turned aggressive and now wants to attack me whenever I am in reach of his beak. He is still separated but for me to change his water and refill his food is a real problem. Unfortunately he lives in disgrace on his own. Is there any chance of him getting back to his old self. I dont have any female ducks, so he isnt trying to protect a partner but I cant understand why he suddenly changed.
I do feel sorry for him on his own and was wondering if I got him another drake to keep him company, would this calm him down or just make him worse. If anybody can offer me some advice, I would really appreciate it.

Regards,