Complete the Story: Black Liquid

Wandering through Barnes and Nobles, I found in the reduced section a book called Complete the Story.  The cover says "Some stories end badly, some end well, and others just keep going on..."  Basically the book is a journal by Piccadilly with a writing prompt on every page.

Starting on the first page (italics show the prompt):

At first, we thought the black liquid was oil, that we'd struck it rich and that we'd be able to retire and live in leisure.  We actually started writing down all the ways we'd spend the money.  Our first choice was food, since our cupboards were bare and had been for a while.  Paul had actually been out checking his snares for trapped animals when he noticed the black liquid and raced home to get us and show us the black gold under the twilight sky.

The next morning, almost before any golden rays hit our valley, we were up and headed back to the spot of the black liquid.  The area covered by the black liquid had grown substantially over the night. And the daylight brought a sight the approach night had hid: death.

Everything the black liquid had touched was dead or dying.  Once healthy trees and plants were now gray carcasses.  Even some animals had fallen victim to the black liquid.

We backed away from the expanding liquid of death in fascinated horror.  How far would the liquid keep expanding?  Would it reach our home?  Our neighbor's house?  The town?  And why was this happening to us?  It was almost as if the forces of nature were out to kill us.  We had barely survived the winter and now with spring we had hoped thing would be better.

We should have known better, being Outlaw kids.  We should have remembered more clearly that in this world, being Outlaw made us targets for Darkness.