Sage

Sages are human reincarnations of Aita, a member of the First Civilization, and the husband of Juno.

Sages are born normally with their own personality and memories but they also possess the memories of Aita. They bear a strong physical resemblance to Aita, and possess a distinctive combination of and  in the eyes.

After Aita, who had volunteered and died after being placed within a First Civilization machine in an attempt to save the world from a solar flare, Juno sought to somehow save him, so that they might reunite some day. To this end, Juno later manipulated the genetic code of human DNA, implanting a hidden trigger that would randomly activate and alter the genetic makeup of the individual, changing their appearance and imbuing them with Aita's memories.

A Sage's blood is required to open the passage to the Observatory, hidden in Long Bay, Jamaica, through inserting it into a blood vial. The Mayan civilization and Taíno people worshiped the Sages, and the Mayan ruins in Tulum, Mexico contained a statue resembling a Sage's head.

Known Sages include the carpenter and explorer Thom Kavanagh, the pirate Bartholomew Roberts, silversmith François-Thomas Germain, and Abstergo Entertainment IT head John Standish.

Sages have been recorded all throughout human history, in numerous regions around the world. According to Bahlam, an Assassin and the father of Ah Tabai, there had been at least eight recorded Sages by the late 1600s - although several Abstergo Entertainment researchers later concluded that the real count was likely much higher.

Reference

 * Assassin's Creed IV: Black Flag