Not only on this forum, but in his books and many videos, Bible and Ancient Near East languages and cultures scholar Dr. Michael Heiser has written about what the Bible reveals to us about the spiritual and demonic realm, of angels and rebelling spirits, the Divine Council, the Nephilim, etc. And much of what Heiser described (he passed away not too long ago) isn't familiar to those of us with just a traditional, Sunday school understanding of the Bible and spiritual realm - as it is a LOT more complex and surprising than we may have imagined.
Here is a really good Christianity Today overview of Heiser's books and conclusions from several years ago, summarizing his understandings about the spiritual realm and its history, per his Biblical research: https://www.christianitytoday.com/ct/20 ... realm.html
And for those of you who aren't familiar with Heiser, here is his bio / info:
About Heiser: https://drmsh.com/about/
Heiser's resume: https://drmsh.com/wp-content/uploads/20 ... e-2020.pdf