I'm always fascinated with dreams and how much they can tell us about ourselves. I strongly believe in reincarnation and have had a number of dreams as a different person, gender, nationality etc. They say souls tend to reincarnate in groups so your loved ones now could have lived with you before in different roles, hence your brother as your son in a different scenario. I'd try matching feelings you feel now and how they could potentially match what you felt like in the dream. It could be trying to tell you something...
Or on the other hand it depends what you did in the hours leading up to your dream. Could just be association and our brains fill in the rest with whats on our minds.
OR I've heard when you dream about someone, something significant will happen to them. May not have anything to do with you but you might see them after a while of being distant or they could move, get a new job, meet someone etc. That's happened to me too.
I dreamt of an old schoolmate I hadn't seen at the time in 8 years, next day they're sitting behind me at a restaurant... o_O