A Demon Seal is a partial copy of a Demon King's own code. They are identical in appearance to the Seven Crests of Lust, Gluttony, Wrath, Sloth, Pride, Greed, and Envy, which are associated with an ancient digimon known only as the “The True Great Demon King,” as well as with a location in the physical Dark Area known as the Gate of Grave Sin. Each Demon King can create and mark a digimon or with a Demon Seal. It forms in the palm of their hand (or claws, in Leviamon's case) and is pressed against the victim's body. The Demon Seal then sinks into, or assimilates into the victim's own code, changing them.
Instances of the Demon Seal being given and infecting Digimon have been recorded throughout the Digital World's history. Its true name is largely unknown, and is known widely as “the mark.”
Once infected with a Demon Seal, one begins to display activities associated with the Sin that a Demon King represents. The Demon Seal has three stages:
Stage 1: The stage that occurs immediately after being given a Seal. In this form, the victim begins to feel a pull towards the Seal's inclinations. The Demon King has the ability to communicate telepathically with them, but they are still capable of resisting. They and their partner also become more powerful and become capable of tapping into evolution by way of using dark power. If a Tamer's digimon evolves during this stage through a Seal's power, they become wild and uncontrollable, but return to normal upon devolving.
Stage 2: If the individual infected with a Seal agrees to any sort of loyalty to a Demon King, the Seal “rewrites” aspects of their personality. They see the Demon King as their master, and fully embrace the vices of their particular Seal. They are no stronger or weaker than they were if they were still Stage 1, but as they are less resistant, it becomes easier to tap into the abilities granted by the Seal.
Stage 3: This is only reachable by Tamers. If a Tamer who has reached Stage 2 evolves their partner for ANY reason, even if the partner is unwilling, the Seal will infect and take them over much as it has their Tamer. The Digimon behaves in an identical manner to someone who has reached Stage 2 or 3.
When progressing from one stage to the next, or when a Tamer taps into its power, the Seal will appear visibly on their bodies and be accompanied by a red, demonic glow.
There are 7 types of Seals:
Wrath: Bearers of this Seal are more prone to anger, and become stronger the more angry they get. It is associated with the Demon King of Wrath, Daemon.
Lust: Bearers of this Seal become obsessed with carnal pleasures and seduction. It is associated with the Demon King of Lust, Lillithmon.
Greed: The bearers of this Seal become greedier for an object or concept of their desire; this can have multiple aspects. It is associated with the Demon King of Greed, Barbamon.
Gluttony: Not just associated with a voracious appetite. Those who receive this Seal become ravenous in their desires and ambitions at the cost of sense. It is associated with the Demon King of Gluttony, Beelzebumon.
Envy: Bearers of this Seal become envious and hateful of other people and their achievements; loathing of themselves and others can also be a result of receiving this Seal. It is associated with the Demon King of Envy, Leviamon.
Sloth: Bearers of this Seal become lethargic and unambitious, and also develop an intense hatred of whatever might keep them from indulging in this. It is associated with the Demon King of Sloth, Belphemon.
Pride: Associated with the sin of Pride, this seal causes its bearers to be more absorbed in themselves and resentful of people they come to see as beneath them. They also become more ambitious and self-entitled. This Seal is associated with the Demon King of Pride, Lucemon.
Ways to Remove the Seal
The Demon Seal can only be removed if the Demon King, for whatever reason, removes it himself, or if the Demon King is killed. In the latter case, no matter what Stage the victim is in, they will revert to the state they were in prior to being given the Seal (excluding, of course, any psychological impact that might result from the experience).
Weaknesses of the Seal:
Digimon of the various Holy Species are more resistant of the Seal's effects when they are in Stage 1. The same holds true for any Tamers who have a partner who is of that sort of species. What's more, a Seal at ANY stage can be temporarily weakened when exposed to Holy Power, allowing the Bearer to behave as if they were not under the Seal's effects for a limited period of time. However, this is dependent on the level and strength of the exposure – wearing a Holy Ring can provide a semi-constant numbing effect that keeps the Seal in check. However, the Seal will fight against this, and if a Ring is removed, the Seal's effects will return much more strongly.
In addition, if a Digimon has a Holy Ring naturally, when it receives a Demon Seal, its negating effects are essentially canceled out.
Uniquely Behaving Seals:
So far, there have been only two Seal Bearer that have shown effects that are unique to themselves. These include Kouichi Kimura and his partner, BlackLeormon. The reason for this is due to their double nature. Because they each share a Dark Power that has two natures equally, the Seal behaves oddly. It allows their power's second nature (the corrupt aspect that takes the form of Duskmon/Velgmon) to grow stronger and then merge them back into one being. While “Duskmon” is essentially a third personality that embraces the Seal, it is unable to do the same to Kouichi and BlackLeormon, whose represent the benevolent half. In short, all three personalities involved – Kouichi, BlackLeormon, and Duskmon – would need to embrace the Seal before it progresses to Stage 2.
