As a general rule of thumb, horror movies like by the mantra of “curiosity kills” and  the demonic possession sub-genre take that rule with passionate zeal.

Take the vastly underrated The Exorcist III: Legion which saw novelist William Peter Blatty turn director, and provide one of the scariest sequences involving an empty hospital ward, a curious nurse, and a possessed killer with surgical sheers in tow. The lesson? Let the cops investigate that mysterious sound, and never turn your back.

Seniors don’t seem to get a fair shake in these films. Case in point is the before mentioned Exorcist III with catatonic elderly patients used as puppets to kill unsuspectedly and efficiently, and Insidious where one of the main demonic figures is an old, witch-like woman. Yet none can beat the gross out, curse dispensing exploits of elderly gypsy Sylvia Ganush from Drag Me to Hell.

Whatever the reason, it seems that females both young and old are prime fodder in demonic possession movies. Regan from The Exorcist is a classic examples, with Linda Blair transformed from a fresh faced 12 year old girl into a grotesque monster. Other examples include the tormented sisters from the Paranormal Activity series and the bendy Nell (Ahley Bell) from The Last Exorcism.  

A common theme in The Exorcist series is the symbolic importance placed on dreams, and there use as a precursor for bad things to come. While The Exorcist III dream sequence takes the prize in the weird shit-o-meter awards, it is the original film which boasts perhaps the most memorable and chilling dream sequence on film, with the blink and you’ll miss it appearance of demon Pazuzu sending chills down spines.

Dis-belief in one thing: taunting ol’ scratch is another. Paranormal Activity uber-male Micah learns that the hard way after berating the unknown entity haunting his Katie. Could be worse: at least Micah didn’t get a face full of vomit like The Exorcist’s Father Karras, or succumb to madness as did demon slaying hero Ash in The Evil Dead 2 .

When it comes to the supernatural, science can be used to detect and analyse, but it is no solution. Disillusioned priest Michael Kovak in The Rite constantly looked to scientific means while oblivious that Satan was near.

Another case in point is John Carpenter’s underrated 1987 film The Prince of Darkness, where a team of scientists are implored to analyse a mysterious container within which inhabits a powerful evil force, poised to bring upon the end of the world.

A great prop in horror movies, Ouija boards are particularly relevant in possession flicks. How else could we have been introduced to the entity known as “Captain Howdy” if not for Regan and Chris MacNeil’s playing with the board? Paranormal Activity also shows the power of the Ouija board as a conduit of evil, with resident asshole Micah using the powerful tool in spite of the objections from everyone around him.

A powerful symbol of religious identity, the crucifix has always been a popular prop in the horror genre (particularly vampire films). However, its success with demonic possession films varies. While triumphantly used in the rite of exorcism as a tool to weaken the unclean spirit and drive it away from its host, one shocking moment of vulgar self mutilation in The Exorcist changed the rules.

Yet it would be The Exorcism of Emily Rose which showed the true power of the crucifix in the battle against evil.

It seems to be a favourite amongst victims of demonic possession: a venture into the dark, claustrophobic space known as the attic. The Exorcist saw Chris MacNeil (Ellen Burstyn) do it while investigating those weird scratching sounds above her daughters room; Insidious also featured a trip to the attic with creepy results; [REC] and Paranormal Activity followed suit with their camcorders, the former capturing one of the scariest moments in recent memory.

A major theme in many of these films is the loss of faith when confronted by true evil. The Exorcist’s William Peter Blatty successfully taps into this theme, by introducing a man of God whose faith has weakened through years of personal tragedy, a dance with the devil awakening his severely weathered belief.