Neinheart is Cygnus's adviser. Neinheart stands beside the Divine Bird and Empress Cygnus. Neinheart is the main strategist of Ereve, as he is the one who directs Cygnus Knights to their quests and certain locations to gather certain information about the Black Mage.
In the future (or rather, the one perceived in the nightmare caused by the Black Mage), when Cygnus searches for the World Tree, Neinheart suggests not to chase after the Transcendent. Cygnus did not take Neinheart's word, and soon fell into the trap that corrupted her and the Cygnus Knights. In the future, Neinheart is the only human on Ereve who did not fall into the Black Mage's World Tree trap in the future, believing that the Cygnus Knights should not take what isn't theirs and thus, he was not corrupted but instead, hiding from the heartless Knights.
Through dialog in Cygnus Knights quest, Neinheart is revealed the older brother of Lilin.