Captain Blackthorn grimaced against the salt air that sandblasted his face. His men were weary, his ship was falling apart and the hold was replete with treasures beyond counting. It was time to head home and enjoy the bounty that years at sea had brought them. As he braced himself against the pressing squall he considered the conundrum of converting said bounty into a transferable asset that could easily be spent without arousing suspicion of the local militia or the jealousy of rival pirates. If only large amounts of wealth could be represented on something as light and unobtrusive as a piece of paper. But then Blackthorn had a idea:
"I know what we'll do! We'll bury it!…"
Teenagers who run away from home to live in the wilderness may become feral. As they become more and more feral, they gain some supernatural powers (a la Peter Pan - ability to fly, things they imagine come true - possibly quite powerful), but at the expense of their humanity and ability to speak, comprehend complex subjects, etc. Maybe they have a leader: the most feral of them all.
A regression into a fantasy childlike state.