Moqorro the red priest- a marginal figure in A Song of Ice and Fire, he only appears in a few chapters, but one could argue his importance to the story will be greater than at first imagined. Moqorro is described as a huge man with black skin and a mane of white hair, with flame- like tattoos on his face denoting his former slave status. He is called the "Black Flame" by the Greyjoy sailors who pick him up on their way to Slavers Bay. Why is Moqorro important? Well, he first crosses paths with Tyrion on the route to Qarth but is then blown overboard in a storm. He is found by Victarion ten days later adrift at sea. How does he survive ten days? And why does Moqorro want to reach Dany?
Spoilers for A Song of Ice and Fire.
Moqorro is a red priest, like Melisandre. He sees things in the flames, tells Tyrion the Selaesori Qhoran will never reach Qarth, and he's right- they are overtaken by slavers and Tyrion is sold into slavery. Moqorro is washed overboard before that though, only to be found by Victarion on his way to Meereen. The Greyjoy sailors want to kill him, but Victarion keeps him alive after the red priest tells Victarion he can heal his wounded hand.
Moqorro was sent by the high priest of R'hllor to seek out Dany and ally with her, as she has been a breaker of chains and the priesthood of R'hllor is encouraging the slaves of Volantis to rise. Tyrion speaks to Moqorro in A Dance with Dragons as they are sailing.
"Dragons old and young, true and false, and bright and dark. And you. A small man with a big shadow, snarling in the midst of it all."
Dragons old and young? True and false? Could this refer to Dany and Young Griff (Aegon)- as a true and a false Targaryen?
And when Tyrion asks Moqorro about the others seeking Dany, he gets this for his answer.
"Only their shadows," Moqorro said. "One most of all. A tall and twisted thing with one black eye and ten long arms, sailing on a sea of blood."
This by the way is what blogger Poorquentyn partly refers to when he expounds on his "eldritch apocalypse" theory- the idea that Euron Crows Eye is going to use the devastation of both his fleet and the Redwyne fleet to bring about the rise of the Drowned God or some other monstrosity- hence the reference to a sea of blood. And there is some imagery to support this in the sample chapter for The Winds of Winter here, where Euron tells his brother Aeron what he has in mind.
I'd like to just say here too- I'm pretty sure the prophecy of Quaithe mentions Moqorro among those who Dany should not trust. Here is what she said.
"The glass candles are burning. Soon comes the pale mare, and after her the others. Kraken and dark flame, lion and griffin, the sun's son and the mummer's dragon. Trust none of them. Remember the Undying. Beware the perfumed seneschal."
Kraken and dark flame? Pretty sure that's Victarion (or the Greyjoys generally) and Moqorro.
"I thought the same, lord Captain... but he knows things. He knew that we made for Slaver's Bay before any man could tell him, and he knew you would be here, off this island."
Even the monkeys fled the ship when Victarion reemerged from his cabin, his wounded hand smoking and charred, after Moqorro's "healing." Afterwards Moqorro served Victarion by foretelling things for him, and counseling him on how to use the dragon horn to bind dragons.
The black priest pointed to one golden band. "Here the horn is named. 'I am Dragonbinder,' it says. Have you ever heard it sound?"
Your brother did not sound the horn himself. Nor must you." Moqorro pointed to the band of steel. "Here. 'Blood for fire, fire for blood.' Who blows the hellhorn matters not. The dragons will come to the horn's master. You must claim the horn. With blood."