By DeAnn T.
Like the other theories, in order to do it full justice it would need an entire book. This subject could 
probably have a series of books. This theory also involves a religious aspect, so, as to not alienate readers from the theory by going too far one way or the other, I will try to keep it relatively neutral so that you can mold and incorporate the theory basics to your own religious beliefs.
So, the generally accepted idea is a “war in heaven”, a war between good and evil, the evil being cast to earth. (References: http://biblehub.com/revelation/12-7.htm, https://www.lds.org/scriptures/bd/war-in-heaven, http://en.wikipedia.org/wiki/War_in_Heaven. Pretty basic. Why were they cast out? This can be a cause for debate and since it doesn’t pertain to ghost investigating (for the most part) I’ll skip it for now. Feel free to ask me sometime and I’ll tell you what I believe.
A general theme, in many factions, in discussing a war in heaven, is that a third of the hosts of heaven, led by Satan, or a “dragon”, were cast from heaven to earth by God.
Here is where the theory of fallen angels comes into ghost investigating. Some of these fallen angels knew precisely what they were getting into and after extensive research; I believe that it is possible that many of those third may have been deceived into aligning themselves against God. They were deceived by cunning, dark, yet charismatic (how else could they entice away a third of the hosts of heaven?? http://www.sharefaith.com/guide/christian-ministries/angels/lucifer-the-fallen-angel.html entities who were trying to fight for their own gain rather than the good of humanity. How would these angels react when faced with the consequences of their choices? Think of the variety of personalities of people you know and then think of all the different ways that say, 20 of your acquaintances may react to a single event.
There are those that are angry, enraged, some are sad, some may be apathetic, smug, and even embarrassed.
It is my personal belief that all of these “fallen angels” are demons, but that they react in different ways. The angry ones swear, scratch, throw things at you, try to possess you, deceive you, etc. Why? Because you have what they want, to not be cast out, to be a part of the life that we live and not a spirit, destined to roam the earth forever without a body of flesh and blood. They are angry at God for casting them out, not understanding that it is their own actions that caused that, or perhaps well aware of why, but not understanding why their way had to have such bitter consequences. Some of the sad ones may just hang out and try to live a life the best they can, either by pretending to be someone who has passed or “making up” a persona, others may hide in the dark, abandoned buildings of the world, hoping to never be found and just trying to stay out of the way while they mourn over their lot in life. Some may figure, “Hey, this is how it is, let’s make the best of it” and may be haunting us for the fun of it and to keep from getting bored. (Ya, that may be a stretch, I know, but it could be…)
Next time you hear EVPs with multiple ghosts talking, listen to it with this in mind. Are they talking to us, the living, or amongst themselves? When they say “Hide” or “Here they come” are they telling us to hide because something is coming for us or are they talking to each other. I tend to believe it’s to each other a lot of the times. Again, something to consider when you listen to EVPs. Listen to them from both aspects and see if you can tell.
As with the other theories that I’ve posted and many, many others that are out there, feel free to agree or disagree with me. The idea of these are to get us all thinking about why we’re hearing, seeing, and feeling the things we do. We all know that there is SOMETHING there and the reason we investigate is to answer all these theories.
This one is one of my personal favorites, as in I think it is more credible than most based on my religious beliefs. I tried to keep this article as non-denominational as I could, but feel free to ask me about it in more depth if this has triggered your interest.