Warning! Spoilers for Rings of Powerseason 2 ahead!
Sauron has black blood inThe Lord of the Rings: The Rings of Power, a unique characteristic that connects him to the original Dark Lord Morgoth. Tolkien never explicitly stated that Sauron had black blood in his works, and no other Maia (the type of being Sauron originally was) had black blood either. This is another area in which Prime Video’sLord of the Ringsseries has taken some creative liberties. However, given what Tolkien wrote about Morgoth inThe Silmarillion, the sour state of Sauron’s blood is a reasonable addition toThe Rings of Power.
In the first episode ofThe Rings of Powerseason 2,Adar and the Orcs brutally murdered Sauron, and this was the first instance in the Prime Video series in which his black blood appeared.InRings of Powerseason 2, episode 6, Sauron (as Annatar) cuts open his hand and fills a vial with his own blood, which he gives toCelebrimbor under the illusionthat it is refined mithril.Finally, in episode 7,the black color of Sauron’s blood is part of how Celebrimbor identifies Annatar as the Dark Lord. So, where does this idea come from?

Rings Of Power Is Drawing From A Deep-Cut Canon Detail
InThe Silmarillion, Tolkien wrote about a battle between Morgoth and Fingolfin (Fëanor’s half-brother), in which the Dark Lord was injured seven times. As this pair continued to battle, Morgoth’s blood filled holes in the ground left by his devastating hammer. This blood is described to have been black. There was no further explanation for this, though it is noted in other parts of Tolkien’s work that Orc blood is also black. Since neither Morgoth nor Orcs were evil by the god ofLord of the Rings' initial design,it can be assumed that black blood is a sign of their corruption.
In Valinor, Sauron was called Mairon, known to be trustworthy with a great love for perfection and balance.

Sauron was originally a Maiawho served the Valar (like Morgoth) and Ilúvatar in the creation of the universe. After Morgoth established himself as the Dark Lord in Middle-earth, Sauron followed and became his lieutenant (after spending centuries serving as Morgoth’s spy in Valinor). The process of Sauron’s transition from an inherently good Maia to the Dark Lord’s servant was slow, andRings of Powerimplies that this corruption turned his blood to the black, sour substanceseen in season 2.
Sauron’s Black Blood Could Actually Be More Than Just Blood
Rings Of Power Takes “Blood” A Little Further
Rings of Poweralso implies that Sauron’s blood is more than the typical red stuff found in living things. After being murdered by Adar and the Orcs, Sauron’s black blood seeped into the earth and congealed, coming together to form a new body over time. In Tolkien’s works, Sauron’s essence or spirit remained after his body was destroyed, and similarly, it took a long time to garner enough strength to take form.Rings of Poweruses the black blood to represent this essence,implying that the lifeforce that seeps from Sauron (and Morgoth, by extension) when wounded is a far more intimate part of their evil being.
Black blood seems to represent the corruption and decay of a being’s own soul in Rings of Power…

This has significant implications regardingRings of Power’s Nine Rings. Celebrimbor unknowingly used Sauron’s black blood as a substitute for mithril when making the Nine. Thiswill likely create a strong connection between those who wear these Rings and Sauron, possibly explaining why the recipients would become the Ringwraiths ofLord of the Rings. Ultimately, black blood seems to represent the corruption and decay of a being’s own soul inRings of Power, and since there are many more yet to be corrupted, we are sure to see more of this dark substance flowing before the end.
The Lord of the Rings: The Rings of Power
Cast
Set in the Second Age of Middle-earth, The Lord of the Rings: The Rings of Power explores the forging of the iconic rings, the rise of the Dark Lord Sauron, and the epic events leading up to the stories in J.R.R. Tolkien’s classic novels. The series chronicles the creation of legendary characters and the historic alliances and rivalries that shape the fate of Middle-earth.