Ages ago, when there was just Heaven and Hell, an Archangel slew an Archdemon, but not just any Archdemon - The Archdemon. Using an ancient weapon of mass destruction, they destroyed the demon and lead Heaven into song and praise for the new era. In this new era, humanity was born. However, when humanity became twisted and sinful, the demons were drawn to them and began to take over human minds (or possessing them). This was when the Archangels created a barrier called the 'Veil' to keep evil at bay and away from humanity. As humanity's sin grows, the Veil weakens and so the angels needed to look for outside help. They found it in the most unlikely of places at that: humans. They would select a few humans ever hundred of years to work for them to keep the world at peace - especially with a new Archdemon rising in Hell and assuming the throne of the most powerful demon now in existence... Well...maybe not...
You see, he was a loyal slave to the previous Archdemon and decided, using his newfound power, that he would summon his overlord's spirit and bind him in the spirit of a human to go undetected by the angels. This human had no idea what his spirit truly was and went on living life as a normal human. This is where things get interesting. This human has spiked some interest in Heaven and they're wanting to use his powers as a protector of the Veil. Now every human needs an angel companion to accompany them for awhile (just to make sure they're worthy). The companion chosen for this human is the very Archangel who slew the demon so many years before!
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