“How will I know who’s a demigod?”
“By sight. Halflings have ichor running through their veins.” When I looked at him blankly, he sighed. “The golden blood of the gods?”
“I have gold blood?” I asked incredulously. At this point, why not, I thought ruefully. Hell, I can probably fly.
“Not in color,” Hades clarified. “In essence. Though it does affect their appearance.”
“They look gold.” At my disbelieving look he sighed again. I thought about offering him an inhaler, but he continued. “Gold hair, skin, eyes—they practically glow. Surely you’ve met a demigod, either here or on the surface. It’s a useful marker we decided on long ago. Accidentally killing or cursing another god’s child is rife with political complications.”
Ichor is the golden blood of the gods and is deadly to humans. The blood is enhanced by the divine diet of nectar and ambrosia. Actually, it’s been hinted at that the gods are immortal because they only eat and drink nectar and ambrosia. As in if they would become mortal if they ate human food. Food is often binding in mythology. Mortal food makes souls mortal. Food from the Underworld makes souls, living or dead, bound to that realm. I didn’t stick to that line of logic in my story. Persephone eats both the food of mortals and the food of the Underworld with no ill effects.
There’s an interesting myth about a man named Talos who was created either Daedalus or Hephaestus with single vein of ichor nailed to his spine in such a way that it was stopped up from entering the rest of his body. Oh, and his body was made of bronze and had wings. The ichor made him super strong so he could protect Europa and her island.
When the Argonauts sailed past Talus threw rocks at them to protect his island. Medea either convinced him to remove the nail holding the ichor contained within his body, or removed it herself, releasing the ichor and killing Talus.
In my books, Ichor is responsible for giving demigods their golden coloring. It’s also the source of the gods divinity and power. Ichor is going to have a pretty important role in the next trilogy, I’d tell you more, but you know… spoilers.