In times of plague, hunger, or war, the children of Kalos' peasantry were often left to fend for themselves – either because they had lost the parents who would care for them, or because their parents had abandoned them out of desperation – and even in relatively prosperous eras, there were always orphans and runaways. Kalos' forests became the destination for some of these forgotten children, who hoped to survive in them by hunting or pass through them to a friendlier land, but many found in them only an early grave.
Yet there is a certain magic to these forests, where Xerneas the life god cast a spell so long ago, and the children who perish here, if they so choose, can gain lifespans which dwarf those of their human bodies by possessing the stumps of trees. These children become Phantump, but dying has changed them, although not because they are ghosts or trees or pokemon now. The transformation comes while still human, from the loneliness and bitterness of being left to die and trying to survive in vain.
Phantump find in their afterlife a friendly community, for the spirits of the forest – even those of the animals which often devoured them – are far kinder than Man. However, although they do not seek revenge, their view of the human world is colored by their trauma, and they ironically often seek to lead even healthy and loved children to their own deaths and Phantump afterlives, having forgotten in their bitterness towards the outside world the true depths of their terror.
Society can do little for these dead, but it has not forgotten them; today, children are taught from a young age how to train pokemon, should they ever need one to survive.