Arihan was the high-priest of the Order of Dialon, thus being one of the highest ranking members of the Triune. He is present in the second novel of the Sin War Trilogy by Richard A. Knaak.
Arihan was ordered by to stop Uldyssian and his friends and followers before they attacked another temple. It was believed he was being ordered by the Primus, Lucion (in reality it was the demon Astrogha who had assumed the guise of the Primus). However, his plan to break Uldyssian by abducting his friend Serenthia failed utterly, as she was actually possessed by the demoness Lilith. The priests ranking underneath Arihan were sent into a state of panic by the failed plan and a lack of further orders, so they commanded the morlu to go out into Hashir and fight. Lacking any specific orders the morlu and Peace Warders began attacking not only Uldyssian and his followers, but anyone near them in the city. As the chaos ensues Astrogha summons Arihan, demanding an explanation. Arihan blames the "fools" underneath him. Astrogha beckons him to step closer, and after looking at his face he realizes it is not the true Lucion. Seconds later, Astrogha tears through the constraints (it seems he created a sort of "Lucion costume" out of spider silk) and bites through Arihan's neck, killing him instantly.