Diego was a member of the Men of Letters who fought in World War I. His experiences in World War I drove Diego insane "Jim Jones style" to the point that all he could see was "blood and violence" in this world.
In 1925, Diego decided to "fix" the world by summoning the gods Yokoth and Glythur from an alternate reality to "cleanse the world of hate and bring a new paradise." Diego ultimately kidnapped a woman named Sandy Porter to act as a vessel for the gods and performed a ritual to open a rift into the other reality in the Portsmouth Chapter House. Diego succeeded in summoning Yokoth, but Yokoth ate Diego and most of the others before trying to summon Glythur. Luckily, the survivors managed to close the rift Diego opened and bind Yokoth before she could succeed.
In the aftermath, the Men of Letters disavowed the entire incident, banned all the survivors and sealed the chapter house. Unable to kill Yokoth, the survivors and their descendants, led by Diego's family, worked to keep Yokoth sealed up.
In 2018, Yokoth was inadvertently released by hunters Sam and Dean Winchester who were seeking the Seal of Solomon. Trying to stop the Winchesters, Diego's great-grandchildren Marco and Ophelia captured Sam and explained what Diego did to him. Working together, the Winchesters and the Avilas were able to send Yokoth back to her world and end the threat Diego had unleashed upon the world.
Powers and Abilities
As a member of the Men of Letters, Diego possessed a great deal of knowledge about lore and the supernatural.
- Spell Casting - Diego was capable of casting powerful spells.