Are undoubtedly Nakul, Disha, Ram, Priya and the execution of their characters.
I mean I am unable to picture Ram and Priya as anybody else other than Nakul and Disha even though I have watched BALH1 and the main reason is Ram and Priya does not feel like the same character as S1 being played by different actors. Nasha feels like they are completely in the skin of their characters. I have watched PKD as well but it was ages ago and I don't remember much from the show plus Nakul and Disha were more younger at that time so they seemed to have matured as people and actors as well and give a totally different vibe now.
Nakul fits the character perfectly as someone who is rich, borderline snob, stylish, fiercely protective of his family especially his siblings, is a go getter, a lover at heart and very committed. His comic timing is also spot on along with playing a person who is in control and in charge of everything other than his own emotions. I love when he leans towards eating and his medicines for everything he does not want to face. I think kudos to Nakul and the way Ram has been written.
Disha has been more of a surprise to me as I think becoz I have always seen her as a very happy, bubbly and a calm person. Priya on the other may be calm but there is storm within her which can burst at any time and Disha has shown us a very subdued performance where even in scenes she is shouting or insulting she does not go OTT and gives a restrained performance which is believable.
I don't know but there is something regarding the chemistry between Nakul and Disha that even when they have only shared screen place in the 5th episode, I could feel their chemistry since the auto scene in the 1st episode. I hope the writers are careful and fully utilise their chemistry and not give unnecessary plot lines just to create drama.
I think all will depend on the execution of this show storywise and characterwise as if a story which has been seen before too is beautifully made then it can create success like no other. Therefore, I just wanted to conclude that I am watching this show due to Nakul and Disha's acting and chemistry and Ram and Priya's interesting characters and difference between their though process.