Dragapult's ancestors were common in Pleistocene Galar, but the large, slow-moving dragons were easy prey for human hunters, and their long life cycles made it difficult to replenish their numbers. Yet the deaths of their bodies did not remove all of these serpentine creatures from Galar; Dreepy's spirits lingered, as did those of their Dragapult parents, and together they learned a lesson they would not soon forget.

On their own, Dreepy are as weak as other dragon larvae; in a Dragapult's horns, or with the momentum they provide, they are fearsome, living missiles, wider and deadlier than an arrow or even a cannonball. Their ghostly bodies serve them well as projectiles, allowing these pokemon to phase out of and into the material plane to strike with far greater force than a solid object of equivalent weight. The Dreepy enjoy these flights, likening them to exciting thrill rides; their victims are rarely so pleasantly disposed to their attacks.

There is a dangerous trail somewhere in the woods near the Lake of Outrage, where many travelers have been shot dead by sniper fire in the middle of the night. No bullets have ever been found in the victims, nor any motive discovered, but many survivors of these attacks report a Dreepy hovering over them as they fell, laughing maniacally in their faces. Yet it is not only humans they target, not some revenge against being consigned to the ghost type; these pokemon will eagerly sneak into any projectile launcher, and many Galarian shooting sports originated from launching Dreepy every which way, with nary a Dragapult in sight.