Dei are Disciplies of Nox.

Although quite rare, some AI have been known to work alongside biological beings. Dei were a varied group of people, acting as the Agents of Nox.

Nox, the Umbra.

The motivations behind working with non-AI are still a mystery, both in regards to Nox and LOGO. Nox typically led Dei on missions to scavenge for information, and on one occasion, to assault Mora.

Mora, the Architect.

The incident on Moré is precisely what led to the downfall of the Dei, the only survivor being Di. His current connection to Nox, as well as his whereabouts, are unknown. It is unlikely Nox made a mistake, therefore it's presumed that the destruction of The Dei was part of an overarching plan.

Di was a leading rank of The Dei before their disbandment.