Responses
Technically he's been ingesting fog. It was mention some chapters back about how fog is literally in the air and the longer he's there the more it will be in his system and he will become addicted and can't live without just like them. That's why he's slowly is changing cause the fog is digesting
That is true, but I believe it is a talent nonetheless due to Hairen implying it was extremely rare and insane to develop an ability without any direct fog consumption.
MC is a natural talent, it takes talent to awaken the ability even with the help of fog. Then there he is, without consume any fog, he inherited a “truth” ability, so I believed the reason the bird die probably due to him forcefully prying into the truth behind the bird where his ability is too strong and that’s how it end up killing the bird.