During the Liberation of Meridian, Helis was ordered by Jiran to take Itamen and his mother and escape the city to the Citadel at Sunfall. There, Itamen was set up as the figurehead for the Shadow Carja, but the real power resided in the High Priest Bahavas and Helis himself. Despite Helis's efforts, Itamen was averse to human sacrifice, and often retreated to his mother Nasadi when Helis attempted to shape him in Jiran's image.
Avad worked for more than two years to try to return Itamen to Meridian through a spy, Vanasha. Vanasha later co-opted Aloy into this plot, as the latter had also infiltrated Sunfall for another reason. With Aloy's help, both Itamen and his mother were smuggled out of the city by Vanasha and into Avad's protection.
With Itamen's defection, the Carja in Shadow's legitimacy was virtually destroyed.
While Itamen is barely seen, all accounts of him indicate a good-natured boy nothing like his father. He was resistant to Helis's attempts to shape him in Jiran's image, retreating to his mother's protection rather than watch a ritual sacrifice. He seems to be close to Vanasha, even making her a Grazer out of matchsticks (while it wasn't very good, Vanasha was joyful at the kind gesture).