On the nature of iron

[ThriceHonored]

Given the effect of raw iron on a changeling, is it reasonable to theorize that they do not possess iron in their blood? Not all animals use iron to transport oxygen. The Horshoe crab is an example of this with its blue copper based blood . Going down that avenue of thinking would it also be reasonable to assume that their bodies would be somewhat intolerant to foods that are high in iron?

[Satchel]

It wouldn't be reasonable at all to assume that, because the frailty of iron is a consistent facet of Arcadian-derived fae and that's a category that includes everything from mostly-normal living creatures to rock trolls to sentient patches of haze. It's a magical weakness of magical beings, and that means the rules it works on aren't necessarily familiar to the mundane world.

[Master Aquatosic]

not to mention that the iron in living things and their remains exists as a small part of a larger protein of organic elements. And we all already know that combining iron with other materials weakens it's magical powers. But yeah, Satchel's right in that Hobgoblins can be beings whose biology doesn't make that amount of sense. How does a sentient patch of haze even eat? Why don't rock trolls eat rocks? My answer could be a hypothesis put forward by a Null Mysteriis scientist at first, but it wouldn't really apply to all hobgoblins on further inspection.

[Draconis]

I'd say it all comes down to symbolism. Steel isn't as effective as iron against fae, because people think of steel and iron as separate concepts, even though from a chemical standpoint the dividing line is blurry at best. But people do generally think of rust as part of iron, so it burns the fae, even though chemically it's not just Fe any more.

Similarly, most people don't think of blood as being iron-based, even though it is. So I don't think it would affect hobgoblins much if at all.