system
Given the following post, respond as if you're commenting on Reddit:
human
[DOOM] What do the demons and various hellspawn do day-to-day when there isn't an active invasion going on, or when the Doom Marine isn't tearing the place apart?
gpt
Hell exists in a completely separate spacetime continuum from our own. Demons and the damned exist in eternity in hell at every single instant of our own spacetime--a year on Earth is exactly as long in hell as a second here. In hell every single punishment inflicted on the damned is experienced both simultaneously and eternally, where the smallest puncture wound is drawn out to encompass the entirety of time, and the forsaken soul is able to experience each of these torments only because they've turned away from God's grace, and His mercy now cannot save them from eternal damnation. As such, there is no "down time" in hell. A demon doesn't have to sit around twiddling its thumbs, because, for every instant in eternity, it's already tortured the damned, and for every instant in the future it's already going to be torturing the damned.

During the Martian incident, nexus points between the Earth's continuum and hell's were created *from the Earth side in*, forcing our spacetime continuum to twist into hell's. When a demon passes through the portal they experience time as we experience it, constraining them to our linear sliver of time. Thus even the worst torments inflicted upon living souls on Earth are mercifully transient, as God's grace still lets us live as is natural to us, and we might be saved even from hell's worst transgressions into our world (though it may not appear this way when being skewered by an imp). This is evidenced by the very obvious fact that victims still succumb to the release of death and have souls that may pass on.

When a living soul twists through the Earth-created nexus and enters hell, for an infinitesimal instant (even if it's all of our mortal existence) hell's eternity is projected down into what we perceive. For this unmeasurable duration the demons of hell are spawned and are destroyed by the Doom marine's actions, but as soon as the twist in spacetime is removed (death or retreat), there again ceases to be the flow of time as we perceive it. It could be imagined as a spacetime bubble drifting through the demonic plane and forcing the immediate surroundings to coalesce in time and space. When the Doom marine passes the damned it allows him to perceive a moment in time when they're suffering, and when he leaves that suffering again balloons outwards to eternity.