These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Paranormal Activity
Accidental Aesop: For Paranormal Activity 2: Never foist your problems on your in-laws.
Alternative Character Interpretation: The demon in the first one. Despite what is revealed about it in the later installments, more than one watcher thought to themselves that they would probably kill Micah too, if they were demons and he stayed in the place they lived all day and yelled at them for moving stuff or doing anything aside from sitting quietly and never moving or making any noise.
Cowboy Bebop at His Computer: The Netflix description of 3 says it is a sequel instead of a prequel to the series, and that 4 takes place 5 years after 3 instead of 2.
Ensemble Darkhorse: Dennis of 3, probably for being more competent and likable than Micah and Dan. Also, Ben from PA4.
This is a large part of what the demon does in the first film. It spends most of the film just fucking around with Katie and Micah until the last 20 minutes or so when the demon decides to go for full-blown Nightmare Fuel.
In an early jump scene, the protagonists listen carefully after Katie thinks she hears something. After a few moments of dead silence, there is what can only be described as an extended scream/howl, followed by a massive thump. Bricks were duly shat.
The sequel manages to do this with a children's toy.
An infamous scene from 2: during the day in the second movie you get about a minute of silence before everything in the kitchen flings open and falls.
Shortly after the above-mentioned kitchen scene, there's the piercingly loud whistle of the kettle.
Also from 2: Hunter's screams of terror.
Hype Backlash: Much like The Blair Witch Project before it, getting so many reviews dubbing it one of the scariest movies of all time ensures that some people will watch it and end up unimpressed.
It's the Same, Now It Sucks: An already common criticism of Paranormal Activity 2 and the following sequels is that it too frequently uses familiar scenes from the first movie.
The Woobie: Ali in 2. First her parents don't believe her when scary things begin to happen, one day her stepmother wakes up acting like a cross between a wolf and a serial killer. Then, oh, things are looking up! No horror for three weeks! Until you come home to find your family brutally murdered.
Any heroic dog in a horror movie is almost contractually obligated to be the most sympathetic character in the movie. Hence, Abbey. But thankfully she lived.
Dennis in the third film. He did cared for his stepdaughters and wife and wanted to find out about the demon and save his family. Yet his wife dies in front of him and is killed by his mother-in-law. All while trying to save his stepdaughters.
Kristi. The events of 2 and 3 would have been prevented had they just listened to her. Also, Dan (in the second) and Katie (in the third) are mean to her for little reason.
Katie. Imagine being haunted constantly by a demon and spending the rest of your life possessed by it, where you have killed several people including your own sister with no control. AT ALL
Alex from P4. It wasn't her fault that she and her family adopted the one boy the demon was after.