That was great analysis Aparna. I tend to differ in couple of places so here are what my thoughts on the different characters.
Singhania : I do not think he is evil but I think he is just trying to repent for his mistake of marrying Sharda. Whenever he talks to Vikram or Shymalee he is shown to be really nice and infact he understands Shymalee as she reminds of his first wife who he is missing very much. I think he just wants to make sure that he plays the cards such that Sharda does not loot him anymore.
Sharda : She is evil as she married Singhania to just get his money . She does not even try to hide it and is always manupilative. Imagine giving Vikram the milk so motherly to make sure that Vikram does not become a dad . She is a meeti churi. She will stoop to any levels to make Singhania industries hers. Currently she still has not seen Pooja 's game so she is surely for a shock.
Kanhaiya - He just is his sisters chamcha as his sister takes care of him. He hence tries to see that his sister gets her share as he thinks his sister has been wronged. He has shown different characteristics and unlike his sister understands people and relationships and is ready to adapt to them like telling his sister that he is not going to break Shymalee's fast. His ability to think through things is what has kept him and his sister still in the Singhania house.
Pooja - I agree on Pooja she is was a victim of a scheme and Singhana assumed that once his job was done he could give her money as per their deal. But unfortunately Pooja fell in love with Vikram so now she is trying to justify that she really loves Vikram and trying to get back her love .
Raghu - He really loves Shymalee and at the same time his greed does get the better of him. Till now he has been shown to be overtaken by greed but I think his character has a lot to be still seen.
Siddhart - His real reason for playing with Shymalee's life on Singhania's command is still to unfold. I think this shows the weakness in the character as he agreed to make a girl pregnant . This is not something that I think can be justified. So now he doing things as per Pooja shows that he is not able to stand for himself and although he is not evil in law if you are an accomplish to a crime you too are a criminial.
Vikram - He is not evil as we all know he is the hero but again its like Siddharth , playing with a girl's life and agreeing to make her pregnant is not something I think is right whatever be the reasons. He is playing with emotions of Shymalee and he knows that and is guilty of that.
Mirror Mirror on the Wall , I think that all the above have shadiness in their character . But if I have to choose one I have to go with Sharda at this point