How did demons get into heaven?

Although my reality is confined to sensory experience, I believe that there are beings that exist in the subtle realm beyond. But how did *asuras* get there? Wasn't heaven only for the good, *sukhumataraṁ*? And without them, what battle could take shape? Is it just dormant tendencies [fantasies] that pop-up there? Any account of *asura* in jhana? Also, does the Hermetic text, 'As above, so below', register within Buddhist circles? From Sakka's Questions comes this: > ‘When a Realized One arises in the world, perfected and fully > awakened, the heavenly hosts swell, while the titan hosts dwindle.’ > ‘yadā tathāgatā loke uppajjanti arahanto sammāsambuddhā, dibbā kāyā > paripūrenti, hāyanti asurakāyā’ti. From Dialogues of the Buddha Vol 2.