I think that's why they have recognised this and are turning Sultan into one, he was supposed to be an antagonist so far him also he winds up RK on sight but that's about it. Which has been cool, because I kind of like him but if he becomes evil through and through then it could be entertaining, I wonder what they have planned.
I strongly believe that there's some past connection b/w Sultan n RK..I had this thought as soon as he appeared in show.Now his mother's news is making my assumption true..don't know whther he'll b his bro or not..but definitely he's not angry wid him only coz of Madhu.