From my point of view - she was always negative...I have allergy in real life and reel life when people are extra sweet and always offering their free services(help)..Barkha entered RaDev's life after learning about purohit situation on televisions, news paper, and other media sources when Dev kidnapped Radhika. She took advantage and planned very well to enter RaDev's life when Radh was weak because police was after dev. Also she offered to go to Purohit bhavan to cure dadaji so she can gain trust of dev and radhika and become good in everyone's book at purohit..she mentioned that she is doctor but no one has proof...I pointed out in one of my post how come barkha became so called doctor when radhika just started the college. I feel that she told rohan where radev were hiding purposely...she was probably shocked when Dev came back during the raj tilak of rohan and saved radhika...so she continued to stick around purohit bhavan...she planned the engagement with Padma(padma was very sad at tht point in her room)...also she may have saved rohan from the accident and took him to hospital..she thn took rohan and tortured him...she said yes to marry dev but dev wasn't giving any attention to her...so realized that she couldn't marry him and tried to get in good books of dev again by telling lies to dadaji, radh, and dev...and ofcourse we knw what happened afterward...she is mastermind from day 1...