I just recently posted about Alex when it hit me, how about Yug??
I believe that if Yug is a central character in this show, as an orphan he probably has an important backstory that we have yet to find out about. Currently there are 2 important families in the house: Palekars and D'Costas.
Palekars: I would really like to believe is somehow connected to the Palekar family. It would make a lot of sense, especially since in the future he is likely to become a part of their ghost family. Of all the people in 25 years, he is possibly the only one who has been able to stay in the house for so long. Maybe he has some connections to the house and hence the ghosts are unable to drive him away. Also, he was hugging their family portrait the first day he came in, so it would be quite adorable if they were to become his family.
Assuming he was born around the time that they were killed, that would make them all 25 years older - or an entire generation older than him. It is unlikely he is Riya and Ishaan's siblings then. Also since it seems both of them were pretty young and not married when they died, I don't think he is either of their sons either. Is he possibly one of their aunt's or uncle's son?
It would be quite interesting to find out about the Palekars' lives when they were alive. Since they owned such a big mansion, they were quite rich and had some status in Bastora. Hence people would've definitely known about them...
D' Costas: I highly doubt Yug is related to them as it is quite clear he and Sophie will pursue a relationship later. What I feel though, is that Peter has some knowledge and connection to the Palekars and very likely their deaths. He seems to be quite wary of the house and shows some negative feelings towards it. Maybe his previous wife's death had some connection to their mansion? If he is a minister, he likely had some connections to them in his youth (maybe he was Ishaan's friend?).
A lot of mysteries to solve and I'm betting on Yug+Sophia to uncover them😉