I find Anami and Narottam's relationship quite interesting.
Like you mentioned, it seems that Sudha is going to use Anami to deliver LM the pain that she was given. And she's going to do that through Narottam.
Now Anami can easily and quickly recognize those who are double-faced like she has with Pujan, but that's because their actions can give you a hint to this. Pujan is always murmuring, looking for the weak link in a room, and has made his hatred for Anami well known. While others are melting, Pujan continues to object to everything related to Anami. Yes, so does Baldev and Vikramaditya, but they are not objecting just for the sake of it or continuously bringing up Avdhoot's adoption. That's why Pujan stands out.
But on the other hand, Narottam has done nothing of that sort and no one knows about Narottam's dark side. When Anami first met Narottam, Poonam told her about Narottam's sad state. After that whenever Anami has met Narottam, he has always mentioned something or the other that he's not allowed to do. He's a shadow who isn't seen too much either which makes him blend in that much more.
For Anami, Narottam is a brother she can speak to freely and share her problems and plans with. Because she has trusted him. The day she sees him for who he is, she'll be heartbroken once again. She's already lost 2 brothers. First Ladoo because her Matlabi Mataji tore her away from her family. Then Vatsalya because she never knew her twin brother.
But for Narottam, Anami is just a means to the end.
Now why I call this relationship interesting is because right now both are on 2 opposite sides of a fence. That's why yesterday evening I was glad to see that even the CVs symbolized that when they showed both standing back-to-back on opposite sides of the railing. One is the light, while the other is the dark. But slowly as both get to know each other things will change. Anami will become more calculative and a shadow, while Narottam will turn towards the light, the brightness, the honesty. Or at least that's how I read the scene.
Now Narottam's expression didn't really have me confused. Somewhere it seems that he may have had something to do with Vatsalya's death. Maybe not directly, but he knows who did it or why it was done. But he didn't seem afraid really. It just seemed like he knew, but he also knew that Anami would never be able to get to the root of it.