In a mission in the Dreadlands, Delios teamed up with Valla. She found him crude and abrasive, and he set her nerves on edge, but their mentor Josen insisted that they work as a pair. They located a demon in hiding in some ruins—Draxiel, a servant of Mephisto. The demon was able to manipulate the demon hunters against each other, and they were only saved by Josen himself.
In 1285, Delios encountered the demon Valdraxxis in the town of Holbrook. He was able to wound it, but succumbed to its corruption, and massacred the town's inhabitants himself. He then proceeded to a bordello outside Bramwell, where he stormed into the establishment, killing everyone (a bodycount of fifteen victims).
Josen was soon able to track Delios down and "deal with him."