Dang, Well, I really hope mine doesn't go rogue on my fish, sorry for you pleco
I find that with my feather fin, as long as he has his own hiding space, he is OK. He hangs out at the bottom of this artificial stump, and as long as nobody invades his stump area, he's very calm and not aggressive. When he does get aggressive, he doesn't even get too feisty.
Part of it may be that he was not the aggressor in the group tank I purchased him from. I always try not to get the most aggressive fish in the tank, especially if they are going in my community tank. I know that it doesn't always work out this way, but I've been having good luck selecting the more mellow of the tank residents.