No one mentioned it when I posted the sketch, but the little Earth pony has strange markings on her head and sides. They’re known as “The Alicorn’s Favor” and it’s shown up now and then in the last few centuries. As the penultimate mark of shame, these ponies are almost always killed before they reach the age of two. In my possible story this little pony has been protected by loving parents for long enough that she began to hear voices and gained strange intermittent powers.
 
When, of course, her parents weren’t able to hide it any longer, they were killed protecting her while she escaped. She lived alone from that point until she met the ruin explorer. Bound by a common goal, the two became the family neither still had. They face challenge, danger, adversity, and heartbreak as they struggle to discover why the world has gone so very wrong.
 
In the final war between the two, their allies and the vicious regime, the ruin explorer falls and the little Earth pony breaks… and in doing so rouses the slumbering consciousness of the Ponyverse itself.