Auris was the last surviving member of the dome-dwelling Aurons and Piper in the magical illusion of Pirra inside the dome.
Auris was a member of the Dome-Dwellers; a branch of the Auron tribe who chose to use their magic to make an illusion of their lost home Pirra than to accept its loss and move on. At some point he became the last member of his tribe due to a lack of children being produced, and so took the position of Piper and the entirety of the Auron's magic for himself.
The Isle of Illusion
Auris met with Lief, Barda, and Jasmine when they breached the dome to search for the stem of the Pirran Pipe. He welcomed them to "Pirra" with an entourage consisting of the illusions of other Dome Dwellers, but his spell failed when Jasmine pointed out the falseness of his kingdom. Auris cursed them for ruining the spell before curling up beneath a glass statue of Auron the Fair and focused all his will on keeping the dome standing. However, because of his interference, a pack of Arach were drawn to the warmth of the statue, and the largest one killed and devoured Auris.
Auris was raised to believe in the illusion of Pirra over reality itself. As such, he was very close-minded to outside opinions and did everything in his power to keep the illusion of Pirra alive.
As the last of the Dome-Dwellers, Auris had the entirety of the Auron's magic at his beck and call. Most of this magic was used to keep the dome stable, but he also created the illusions of the other Dome Dwellers.