A common theme within all of the „Insidious“ movies is that the dead and other spiritual entities will try to deceive you. During the first film, Josh learns that he used to astral project (his soul left his body) when he was a child, just like his son is doing now. When someone does this, it leaves their body open for spirits and demons to possess it, and that’s exactly what happened to poor Josh.
As it turns out, Josh used to be stalked by the ghost of an old woman dressed in black (Philip Friedman). She tried to befriend him and manipulate him to leave his body so she could steal it and live again. When Josh enters the Further (where the spirits live) to save his son, the old woman returns and invades his body. When he wakes up, everyone assumes he’s who he appears to be. However, a picture reveals the truth. The entirety of the second film is about proving that Josh is possessed. Similarly, there’s also the eerie moment in the sequel when Carl discovers he isn’t actually talking to Elise’s spirit.
There are two instances of mistaken identity in „Chapter 3.“ First, Quinn thinks the spirit she’s reaching out to is her mother. However, it’s actually the man who can’t breathe trying to lure her into the Further to live with him forever. In „The Last Key,“ one of Elise’s nieces (Spencer Locke) follows her father’s voice, only to meet the demon dwelling in the basement. In short, when dealing with a haunting, be absolutely sure who you’re talking to.