Is that cold iron thing with faes really a thing? I only learnt of it due to an encounter in pathfinder (they found a cold iron sword and one of my players is a gnome).
That doesn’t sound very fae like, now if he was giving your “perfectly fine” babie Downs syndrome or causing your grandma to die slowly from an autoimmune disease yeah that’s a fae.
The Fae are the explanation for all the “bad” things that happened to people that couldn’t be explained due to a lack of science.