Inquisitor Avernus is described as being a gaunt man with short black hair, wearing black robes and armour and a red and black visor.
In Episode 19 he is introduced as Valin's captor. He wields a double bladed lightsaber. He is also flanked by two Imperial Royal Guards.
In Episode 20 he goads Valin into fighting him, threatening to kill all of Valin's friends if Valin does not strike him down.
In Episode 21, he is killed by 0B-1 after being dropped into lava.