Are the angels who fathered the Nephilim the same ones who rebelled with Satan? Rev. 12:4 says one third of the angels were swept out of heaven and cast to Earth. The ones who fathered the Nephilim in Genesis 6:2 are being held in chains for judgment according to Jude 6 and 2 Peter 2:4. If all the rebellious angels are in prison, who has been working with Satan all this time?
I believe the angels referenced in Rev. 12:4 rebelled with Satan before Adam was created. They will be confined to Earth right at the beginning of the Great Tribulation. Most scholars agree that the ones who fathered the Nephilim were a much smaller number who took on human form (left their own habitation) to marry human women and they are the ones who are being held in darkness for judgment. If so, there have been plenty of rebellious angels available to work with Satan through out all of man’s history.