That's 'cause he's looking at Ideum like he's prey. Even before knowing he's connected to Jaeyi, his vibe was already creep-like. I just hope he doesn't actually assault Ideum, the fact he empathized for a moment due to the surgery makes me hope he won't be a total piece of trash but my expectations for his behaviour are very low.
Yep, indeed because he looks at our precious ideum as prey ... I know there are a lot of stories where there needs to be some big drama for the story to continue, but them there are stories like wild beast warning where it's still cute all the way through and their only issue is not them opening up about their feelings...

Tbh his brother is serving a serious face card that I can't deny, but I dislike him very moment when he smiles because he finds something intriguing about ideum. Mostly because he doesn't see ideum as a person himself, or finds him interesting,.but more like someone related with his brother. I'm not sure how to describe it. He somehow seemed more genuine when they talked about their injuries and how the managed to survive it, and switched again to this icky side.