I think i missed something

I'm sure they'll explain it eventually. I think. Maybe. Who am I kidding. I have no idea what's going on about anything anymore.

probably an aura thing

I think it's like pheromones or an aura that they can release. Dad's the top dog vampire so his are really strong. The smell/vibes are overwhelming. It's why Minhoon gets so scared around him (the really strong mint in a previous chapter helped mask the smell and he was less affected by dad's scent then) He must've released a bunch to test Gunchan, and when Edric opened the door there was too much in the room for him to be able to go in comfortably.
And I think that humans are unable to detect/smell it? Or maybe they're supposed to be really affected by it.. I'm not sure which. But Gunchan was somehow able to detect it/or not be overwhelmed so now Dad is more interested in him.

I think the same thing and i like ur explanation

Gunchan kinda has more immunity to it more than others that's why Daddy has his eyes set on him ε=ε=(ノ≧∇≦)ノ

Like twilight... hohoho