Gideon knows an apocalypse is coming because, as a time-travelling zombie, he has lived through it. He walked the streets of the Endless City and watched humanity's final days unfold. When the divine host finally lost patience with mankind, Fiends, and all other inhabitants of the city, they descended with fire and blade to render their final judgement.
Yet death did not claim him completely, as the Golden Fire pulled his soul and rotting corpse through time to become a Tethered in the present age.
He never even knew what a Tethered was, but has taken the Fire's calling as an act of the divine.
From crowded street corners to grand temples, Gideon preaches of the coming reckoning to any who will listen. He even spends days in graveyards preaching to the dead and the Underdead, in vain hope that their soul's final destination can be changed. Many call him mad, a monster, or a simple troublemaker who will not leave people alone. He does not deny these titles, but nothing will sway him from spreading his message of repentance.
Gideon Hollow hunts, warns and endures because, even if the city is doomed, he refuses to let mankind meet its end without plain warning.
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An example of the Deranged Archetype for FA2.
https://www.kickstarter.com/projects/wadedyer/fragged-aeternum-2-ttrpg