Pranjal was the good one and Daksh the evil one. Palak and Pranjal fall in love and get engaged. Daksh is obsessed with Palak, but gets engaged to his friend Keshvi. There's a car accident with all four later on, and Daksh takes on Pranjal's identity, saying that Daksh died saving Pranjal and Co. in the crash.
Daksh married Palak as "Pranjal" and his fiance, Keshvi, marries his cousin Ishaan.
Daksh goes through changes while acting as Pranjal, but when the truth gets out that he is really Daksh and that Pranjal died, Palak naturally flips out and hates him
Eventually, she realises that she loves him and they get ready to re-marry as Palak and Daksh but Pranjal re-enters the picture (everyone thought he died)...
He holds Daksh responsible for stealing his love away and turns evil trying to get her back. So now pranjal is the bad one and Daksh the good one.
Confused?