Paranormal Activity/WMG

Katie and Kristi have
Because of the events at the end of the third movie,

The Slender Man is the Demon.

 * The Demon could very well be Slender Man. The strongest argument for this is the fact people end up filming themselves continuously. Yes, it is said so that they can catch activity on tape, but the lengths to which the protagonists go becomes a little obsessive. Putting a camera in nearly every corner of nearly every room in your house because of one break-in? Not obssessive at all. Also, in the third film, Kristi mentions to her mother that 'Toby', the Demon/Imgaginary friend is tall.
 * The Demon could very well be Slender Man. The strongest argument for this is the fact people end up filming themselves continuously. Yes, it is said so that they can catch activity on tape, but the lengths to which the protagonists go becomes a little obsessive. Putting a camera in nearly every corner of nearly every room in your house because of one break-in? Not obssessive at all. Also, in the third film, Kristi mentions to her mother that 'Toby', the Demon/Imgaginary friend is tall.

Dr. Johan is the most badass demonologist on the face of the planet.
A demonologist who can't be bothered to fight a demon that's the worst his psychic medium pal has ever seen? What's he so busy with that he can't show up to help out?

He's in Prague.

Beating the shit out of Cthulhu.

With his BARE HANDS.


 * So he's Marconi from John Dies at the End.
 * Who the hell is Dr. Johan?
 * He's a demonologist that the psychic repeatedly recommends but never actually makes an appearance in the movie.

This movie takes place in the past of the Warhammer40000 universe.
The demon comes from the Warp, (explaining it's alien footprints and dickish behavior,) and Dr. Johan is the Emperor (also Batman).
 * The cultists in the third film worship Khorne. The Demon is a Daemon of Khorne; it is decidedly violent, but as of yet, nowhere near as strong as it will be in the 41st millenium. It can't attack people constantly, but as nerves get stressed and tensions run high, the negativity and rage feed it, allowing it to act out.

It wasn't a demon at all
It was old man jenkins in a rubber mask trying to scare off those kids so he could get the Spanish doubloons underneath the house!
 * And he would've gotten away with it too, if it weren't for those meddling kids and their dog...

Katie wasn't possessed when she stabbed Micah.
In the alternate ending, Katie was just scared out of her mind. She grabbed a knife and stabbed what she thought, in the dark and in her panicked state, was the demon.
 * Which explains why in the two alternate endings, she either goes catatonic or slits her own throat.

Katie isn't the only one being mildly possessed.
Why is Micah such an unhelpful jerkass during the film, I wonder?

Katie was born to be a witch. The demon just wanted to be her familiar.
And her bodyguard. It knew Micah was bad for her and was jealous of his relationship with her. Anyone who ever dated a woman who has a pomeranian knows exactly what I am talking about. Katie likes being possessed once she gets used to it — it's why she smiles so much. She and the demon go off to live happily ever after, fighting crime. Without Micah to hold them back.
 * Well, the demon did slash out Micah's face in the photograph...the idea that it doesn't like Micah specifically doesn't seem too far off.
 * So the demon is essentially a non-romantic version of a Yandere?
 * After the events of Paranormal Activity 3, that is pretty likely.
 * Then why was it Kristi's "imaginary friend" and not Katie's?
 * Maybe the demon got more interested in Katie as time went on?

The Demon is Katie
Connected to the WMG above. Suppose Katie really is a witch, but she doesn't know it. Her repressed witch side manifests as psychic phenomena, that strikes out at people she knows and acts out her unconscious wishes. The phenomenon carries to every member of her bloodline. In the first movie, Katie's repressed anger at her Jerkass boyfriend Micah manifests as a 'demon' that torments him. In the second movie, the mother's demonic aspect attempts to 'protect' the baby at all costs from outside threats (read: everything, including the unaware human aspect of the mother). In both cases, both personalities merge, however, in Kristi's case, her human side wins out, due to her overriding urge to protect Hunter. However, Katie's repressed anger bites her in the ass, and her Ax Crazy demon persona takes over. Hunter is going to be some kind of mage messiah, and now that Demon!Katie has him, she is free to corrupt him in any way she pleases.

In PA 2, the demon specifically staged 'break in...'
...so that Dan and Kristi would get the cameras installed and record everything. Just to keep fucking with them more.
 * It seemed implied to be just that the demon was responsible for the 'break in,' given that nothing was taken except a rosary necklace.
 * And, as revealed in the third film, the tapes that documented their experiences as children. The demon couldn't have them seeing that...

The Demon is actually a Vampire from the Old World of Darkness
Ok, this one is tough to rationalize, but it works for both movies. The Demon is a Lasombra, which is why it never appears on the video cameras. It has high levels of Dominate (allowing it to possess and control Katie and the Mother), and Thaumaturgy, allowing it to perform acts of telekinesis. The shadow control comes part and parcel with being a Lasombra. Throughout the movie, it's slowly ghouling Katie and the Mother, until it can Dominate them remotely (ie. the end of the film). This is also why it seems most active at night. It also explains the bite marks.

The Demon has some connection to the number 3
All its attacks tend to come near the vicinity of 3 am.
 * I've heard that 3 AM is the strongest hour for occult/paranormal things, like witches and demons.
 * Supposedly 3 AM is the magic time because it is the opposite of 3 PM, which was (traditionally) the hour of Jesus's death on the cross, so this is when demons appear to mock the faithful. Or so Ian Holm told me...
 * This troper knew there was a reason he kept waking up at 3 am last year...

Someone cursed the family in Paranormal Activity 2
The demon only seemed to get strong enough to mess with a large amount of stuff after an extended period of haunting in both movies. However, we see someone/something had completely trashed their house in the beginning of Paranormal Activity 2, way beyond what the demon should have been capable of that early on. Not only that, a necklace that Katie had given Kristi in their youth had been stolen yet nothing else had.

The necklace had some kind of demon-repelling qualities to it and after being stolen, it freed the demon that had tormented them as children back into their lives, very likely intentionally.

It was all a Xanatos Gambit by the demon
Aside from the obvious "he's fucking with us" scenario,  gives the impression that the whole thing was planned.

There will be a, focused on Ali.
Because this is a potential Cash Cow Franchise, some THING will come after her in time for Halloween 2011, in order to keep the connection to the previous two. And it will happen in a college dorm in order to give the most potential succeeding movies.
 * That sounds like it would kick ass, and I know college students everywhere wouldn't sleep for weeks, but the PA 3 teaser indicates it will be yet another prequel depicting Katie and Kristi's childhood, AKA the initial haunting.
 * According to Dread Central, Oren Peli has said that it will also partly be a sequel with its focus on Possessed!Katie.
 * This is entirely a prequel. Oren Peli might use that idea for the fourth one, but is not present in the third.

The Demon is actually a witch: The Golden Witch Beatrice
It's been implied that The Demon made a pact with their ancestors who wanted to get rich. Beatrice made a pact with Kinzo so he could get rich. It's been implied that The Demon did it For the Evulz. Beatrice also did it For the Evulz (most of the time, anyway), making the both of them troll. And of course, you couldn't forget that both series are based around Kill Them All concept! You can't deny this: The Demon of the Paranormal Activity and The Golden Witch Beatrice from Umineko no Naku Koro ni are the murderer are one and the same!!
 * Beatrice is a major Troll, so that would explain the demon's major sadistic tendencies, but then where are her minions? The Stake Sisters? Ronove? And shouldn't Battler come leaping in, pointing his finger at the footage and explaining how it is all fake?

The reason the demon goes after Katie is because her family possesses a Denarian coin.
Well, we already have seen a Fallen that manifests as a living shadow.....maybe Nicodemus is younger than we think...

The demon really was feeding off the fear.
In both movies. When was the biggest demonic event? After someone was freaking out. And it used its new found energy to stir up more fear and panic to become even stronger. He wasn't doing it For the Evulz, but to get stronger. And after being exorcised he didn't have enough strength to repossess Katie.

The Demon was fighting Kristi's maternal instincts
It would explain why He/She/It didn't snatch Hunter when possessing her.

Kristi and Katie made the deal with the demon as children, causing the curse that spans first two movies.
The PA 3 seems to be about their childhood, and this theory certainly makes sense with the storyline so far.
 * Then why are they so baffled as to why the demon is after them? Also, PA 2 seems to imply that it's their grandmother who made the deal.

will still revolve around Ali.
Part of the viral campaign for the movie is a flyer advertising "Darren's Timeless Memories", a company that transfers VHS to DVD. Ali will discover the tapes of Katie and Kriti's childhood and use this company to watch the movies in an attempt to discover what exactly is happening. The movie will cut between the tapes of Kristi and Katie as children and Ali in the present day.
 * Oren Peli has said that part of the movie will focus on Possessed!Katie, so it could very well also end up showing Ali. Perhaps Katie will show up while she's watching the tapes, and the security cameras will record it?

The next PA film will revolve around Ali
It'll be a few years in the future and have her desperately searching for her little brother Hunter, and looking for incidents similar to what happened to Katie and Kristi.

This troper had been waiting for the house to catch on fire, except it never happened. However, how could they have covered up the deaths of ? Unless their bodies were put in their house and set on fire...any injuries they have would be unnoticeable, thanks to the fire.
 * If I recall correctly,
 * If I recall correctly,

The Demon has Yellow Eyes...
Katie and Kristi were two of it's special children. It even culminates the third movie by killing their mother...
 * And even burns their house down. Might be on to something here...

Katie and Kristi's Grandmother is Flemeth from Dragon Age
She's survived into the modern era, and the whole demon thing is just her using her magical powers, or perhaps her abomination side to spy on and mess with the family. Her entire aim is to possess Katie or Kristi, because that's kind of her M.O. The Grandmother even looks like Flemeth, is a creepy old lady who acts nice at first, and is possessed by a demon. Fits surprisingly well.

The Demon is Nyarlathotep.

 * The cultists from the third movie offered the first born son to Nyarlathotep in exchange for wealth and prosperity. Nyarlathotep is a sinister and highly intelligent entity. He's just screwing around because that's what he does. He's just hanging around the family waiting for someone to have a son, And seeing as all horrors in the world stem from the Mythos, it's entirely possible 'Toby' is just another one of Nyarlathotep's avatars.