My house is not huge but they do have plenty of space to roam and stay away from each other.

I've gotten to the point that, when I'm home, I let them out together. Sometimes they are fine with it, but sometimes they're not. I'm hoping they'll eventually get used to each other again to the point that I don't have to separate them when I'm not home.

The oddest thing, to me at least, is that when it's time to eat and they're both out, they seem to be greeting each other, bumping heads and rubbing. Not always, but often. It gives me hope that they may get back to being "brothers" again.