Betrayer

"Saving your people will not bring you peace, only make the burden you carry worse."

- The Betrayer to the Doom Slayer

The Betrayer, real name Valen, is the former commander of the Night Sentinels that committed treason against the realm of Argent D'Nur to bring back his dead son. He is one of the supporting characters in Doom Eternal.

Background
Valen was one of the Night Sentinels commanders who led countless battles against the forces of Hell. However, after his son perished in battle, he betrayed his kin to bring him back. Valen made a deal with the Hell priest, Deag Grav, to resurrect his son in exchange for leading him to the Wraiths. This led to the fall of Argent D'Nur as Deag Grav used the energy of the Wraiths to empowered Hell's demonic legions to overwhelm Argent D'Nur and Valen's comrades were cut off from their world and scattered in Hell. But Valen did not gain back his son; instead, Deag Grav resurrected his son in the form of the Icon of Sin. Guilt-ridden by what he had done, Valen chose exile in Hell. Since then, Valen is condemned by his people as the Betrayer.

Doom Eternal
The Doom Slayer meets the Betrayer to retrieve the Celestial Locator to track down and kill all the Hell Priests to destabilize hell forces on Earth.