Bramblin are undeniably ghosts – there is no other way to explain how they phase through obstacles – but the question of who they were in life is one on which the world is yet to reach consensus. Early scientists considered these pokemon to be what happens when a spirit is tangled up in vegetation, and held their existence proves that souls have mass; some lunar pokemon still attribute Bramblin's existence to souls weighed down by gravity. Yet Bramblin spawn in deserts, not forests, and the afterlife is not always visualized as above this world.
Perhaps folk wisdom, in this area, is superior; one remembers the common tale of serfs tied to a plot of land their whole lives, dying with regret that they could not see the world. Perhaps Bramblin were born to grant these wishes. Supporting this theory, Bramblin are not vengeful ghosts, but happy ones.
Bramblin and Hoppip often associate with one another, for both are diminutive grass pokemon far too small and light to resist even a gentle breeze. It is the same wind currents which blow both species here and there, and often quite literally into one another. They form close but short-lived friendships, and hope that someday, in some vortex or storm, their paths will cross once more.
At times, they do, and there is something to be said for the sheer joy of any Bramblin/Hoppip reunions. But if they do not, the Bramblin do not miss their old friends too much. For there is a vast world out there to explore, and they are happy to float wherever the wind takes them.