Fresh home from war, two brothers must defend their family when one brother’s past comes back to haunt them.

That's what I was leaning toward. Two flawed characters. One more flawed then the other.

Yes, let the brother have the revelation. But that revelation makes him the central character. I think you have to decide who the central character is. Or are they both central characters? Like Training Day ?

Wouldn't it also be easy to relate to a character who has to clean up after his brother's mistakes all through their lives even after death? What if the careless/reckless brother has the revelation about the way he has been living his life only to realize it's too late and his brother still has to clean his mess up?