Notes on the realms
Anything I think of that has to be properly developed into lore. Mostly contains headcannons and tiny lore blurbs.
General notes
Removing the eye and returning it to Xavin would leave his realm in ruin. It would allow other sins to invade and take over his realm unless a new patron of Lust would be appointed, and Chastity would likely perish as she is already in a weakened state.
All the sins, in their god forms, have floating entities that are able to act in their stead, if the need arises. Sometimes those entities can split into many smaller forms and be used as tools of surveillance.
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The realms all have a separate day and night cycle. Where it can be night in one realm, it is the middle of the day in the next. In Limbo, time seems to stand still as the time of day never changes and there is always an eerie mist covering the realm.
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The four Horsemen are the product of a collaboration between Wrath and Greed. Wrath has full control over Conquest and Death and Greed has full control over Famine and Pestilence. Although to allow the four horsemen to ride the mortal realm, the two Sins have to collaborate for an extended period of time, which is unlikely for either of the sins to actually happen.
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When a sin is gravely injured, the corresponding virtue also grows weaker. This has been made very clear with how Temperance died shortly after Gluttony was killed. Somehow the beings are linked, as there can be no light without darkness. If something happens to a virtue, the sins will know and vice versa. With the removal of Lust from this realm, the virtue of Chastity has been severely weakened, almost to the point where they are a mere mortal. The virtues are working hard on a way to find and retrieve Lust and restore balance.