Satan and 1/3rd of the angels fell in eternity past. There is no gap
between gen 1 &2. Just that in verse one God said He created
everything and in verse two He begins to tell how He did it.
  Only the angels who defiled themselves with women are in chains in hellfire.
All the rest of the fallen angels are deceiving people today as they
always have done. These angels are behind today's UFOs and they will
pretend to be UFO aliens to deceive mankind in the great deception
after the rapture. They have already re-created some of the Nephilim
like they did in Genesis.