The demon from Parker Finn's "Smile" movies has a very peculiar mode of operations. It's largely invisible, and it can induce hallucinations in its chosen hosts. It typically appears to its victims as someone they know, or perhaps a stranger, but always wearing a very creepy smile. For a few weeks, the demon tortures its host with hallucinations, eventually taking over their bodies. Once possessed, the victim themselves would smile horrifyingly, while taking their own life. The self-slaughter is, as the demon dictates, performed in front of a witness. The witness, in seeing a smiling person kill themselves, gives them trauma that allows the demon to pass onto them. The cycle then repeats. 

The "Smile" movies are very clearly about the way trauma can be passed from generation to generation, and how violence and self-harm can create a never-ending cycle. Despite the strangeness of the premise, the "Smile" movies are surprisingly scary,...