Right. Well, um, not many know what really happened here.
The Inbetween is indeed a strange place, with the Tillywump being one of its more peculiar offerings. It is unknown whether this odd curiosity, who towers at a good twelve feet, is a solitary incarnation or one of many, as only one has ever been encountered at a time. Whether it is the self-same one being encountered or various Tillywumps is unknown.
What is known is the Tillywump’s strange appetite for hats. In the Inbetween money doesn’t grow on trees, but hats certainly do. They grow quite abundantly in the “forêt du chapeaux,” Bowlers, Top Hats, Fedoras, Stingies, Beanies, Poorboys or Berets to name a few. Alas the Baseball Cap, though, is nowhere to be found. It is strictly of human design and manufacture and does not grow on trees.
While the chapeau is relatively abundant, the Key Hats (aka. chapeaux principaux, sombreros dominantes) are of a much rarer sort. These Key Hats contain special properties specific and unique to each hat; and these hats, with that slightly magical flavour, are the ones that the Tillywump craves most.
Beyond this the Twigkith (the caretakers of the trees) are doing their best to learn more about this elusive beast (or beasts).