Fae Blood

Fae Blood is — surprise, surprise — the blood of Fae that is a reddish brown colour when it flows fresh but as it dries it turns into a black sticky substance that is surprisingly strong as a bonding agent not only to cover wounds as it is biologically meant to do but also to fix minor repairs on leather, paper, wood, and similar substances. It is water-soluble so it breaks under water and in heavy rain but very heat-resistant. To get Fae Blood is another matter entirely, of course, and it is sold for high prices on black markets, and more often counterfeit than real. An honourable Fae will not give their blood to anyone never mind fill it into neat vials to be sold for profit. Their blood is meant to be an emergency bonding agent mid-fight to fix a ripped strap or aid an ally when setting up a quick camp, you will find Fae willing to cut into their hands for a few droplets for that purpose with ease, but to donate blood for sale? Maybe in times of dire need to their closest friends and allies, but it is not a common purpose. How do black market merchants get their hand on the substance? It is a resource that many low-level criminals harvest if their victim is a Fae — if they succeed to kill one that is. After larger battles including Fae it is not uncommon to see mercenaries and other money-hungry species out looking for dead bodies to loot.