In the original show that LAT was copied from then Kushan is to blame because the girl was having an affair with her uncle, although it had said at start of serial Trisha told Vivaan she liked someone else but then we also hears Vivaan's confession that him and Trisha never really dated, it was more a dare on his part, so whole storyline has went pear shaped, if that had been the case then why show the fight between Vivaan and Trisha on beach the night she disappeared if it was only a dare for a short while months before? The creatives tried to copy the original show and changed it midway for some reason, maybe cause people were starting to guess the plot...sooo of anyone from Swaikak's is the kidnapper, it would be Gaurav in indian version. His motive is that he has been treated badly by Prateek and Lavanya and also they make fun of him...never under estimate the quiet one. Kushan's calls have only came after he found out about Lavanya and Prem, his is more husband trying to make wife jealous type in revenge storyline.