An interesting question is when the devil and his angels fell from heaven. Most believers assume they were cast into hell in the distant past, but this isnt clearly taught either in scripture or Catholic Tradition. In scripture, the devil is called the "prince of the power of the Air," and "the god of this age." And we're said to struggle against "wicked spirits in high places." Paul also said "the gods the gentiles sacrifice to are demons, and not gods." And in the book of Revelation the devil and his angels are pictured as falling from heaven sometime after "the woman" (who pictures Mary, and/or Israel) gives birth to the manchild. And when cast out of heaven he "knows that he has a short time left." In Catholic Tradition even Augustine and Aquinas placed fallen angels in the sky (the lower heaven.) And this may bear on whether they're explicitely included in Colosians 1:20. "and through him to reconcile to himself all, whether on earth or in heaven, by making peace through his blood, shed on the cross."