The Parents
What kind of parents do they think they are? They shove their kids in the basement of a morgue, make them think their crazy, and for what? Money.
I found the mother particularly moronic, especially at the beginning, when she's mopping the floor. Did she not notice the gallons of blood on the floor as she started to mop? And then when she's covered half the floor she stops? What the hell?
Their children are tormented and possessed, their niece is attacked by their possessed son twice (I'm not sure if he was trying to rape her, or kill her or what, but you know he was going to do something) and then almost strangled during an exorcism, and they don't move, yet after the exorcism gets rid of the demons, they move?! Because of the memories?! I think current demonic activity would trump bad memories any day, at least for people who actually cared about their children.