@Morbo: yes, I can see that happening... but if good can be corrupted, or, in this case, inherent evil can win out, why can't evil be "corrupted" (or at least: diluted) also?
Scenario: The child is now 21. Dad and Mom have gone off to visit her people at the elven village in the Dark Forest, and for the first time, their son has stayed behind. He has a party later that night. Although they usually live in Stormfist Castle, they were spending a few weeks at their cottage in the woods to the west of Glenborus.
The child is immersed in the journals of Coram Bloodclub. A demon appears, reveals to The Damned One his background and heritage, and tells him now is the time to step forth and follow his destiny.
Damned One: "Wow! Cool! What do I do?"
Demon: "You start by performing this ritual to bring down fire and pestilence and destroy Stormfist Castle."
Damned One: "Hey! Sounds like fun! .... uhh... now?"
Demon: "Yes. Now."
Damned One: "Uhh... will it take long? We're having a party tonight at the Dwarven Bread Inn... everyone will be there... Denizen is playing... Uncle Zandalor is doing fireworks out back..."
Demon: << impatient >> "It'll only take a couple of minutes. Just light the candles, chant the words, and the rest will take care of itself." << proffers a book of spells, open to page 666 >>
Damned One: "Ok, ok, gimme that book..." << starts the ritual >> << stops suddenly after only two syllables >>
Damned One: "Wait a minute... there are CATS in Stormfist. I'm not about to kill any cats... Arhu has always been my pal!"
Demon: "The cats have allied with the humans. They must be destroyed."
Damned One: "O just forget it!"
The demon, thoroughly disgusted, blasts himself back to the Underworld. The Damned One goes back to his book.