I don't think that Shiv is going to occupy Vyom's body throughout the marriage as well. So far everything Shiv has done is to drive Vyom away from Sharanya. He wants to isolate Sharanya.
Now as per rumours, his attempted rape of Sharanya through Vyom's body is going to fail because she knows that Vyom is not like that and so she'll be the one to take Vyom's side and support him even after being mistreated by him. Hence Shiv's mission of occupying Vyom's body in that case failed.
Given that occupying Vyom's body for the marriage doesn't make any sense. Because what can be do that will stop the marriage? Really nothing. Any time he tries anything, Sharanya stands up against it and Shiv has to back down.
I do agree though that the marriage shouldn't happen. Reason being is that Sharanya doesn't love Vyom. She's doing it out of a sense of duty and care for Vyom. She wants to save his life and thinks this is the only way to do it. In my opinion, a marriage should only happen when 2 people love each other. I've seen too many marriages of friends and family break up within a few years because the 2 people didn't love each other and therefore couldn't adjust after marriage. I know that TV shows and movies take the creative liberty of showing love after marriage and/or multiple misunderstandings and still getting back together, but that's not how it always works. My point being that if Sharanya doesn't love Vyom, then she shouldn't be getting married to him.
If she does want to save his life, there are multiple other ways of doing it. My paths for Sharanya:
- The Sadhvi seems to know something. Talk to her and investigate from that point forward.
- Odhni keeps warning you. Talk to her.
- You know this has something to do with your accident and surya grahan. So go back to that time and investigate from there.
- Talk to Shiv, instead of being scared of him or threatening him. He seems to be able to use blood to communicate so ask him questions in a non-confrontational way. Get some of the story and then investigate further.
These are just 4 options. There are so many other things Sharanya could do that would save Vyom's life. I feel Shiv's whole point is to get Sharanya to the truth. He is using various means to do it that are dubious, but I refuse to judge a character until their whole story arc has been revealed. I've been burned one too many times when I do that, hence I'm a bit more careful here.
Anyways I'm starting to go off topic, so I'll stop here.