solidsnake101023 said:
Fist off, it kinda sounds like you didn't have a say in the idea and they forced you to do the ending, this is probably why your havins such difficulty. You generally can't do something well unless you enjoy doing it.
Back to the question at hand,
There are 3 kids, this fits nicely with the aspects of Id Ego and Superego.
Id is the aspect of your animalistic desires, it's what makes you want to eat, have sex, and beat up other people who want to take your stuff. supercharge that and one demon could be a totaly animal, who kills one of the other kids.
Superego is the aspect that balances out your Id with morality. if this kid is possessed by a superego the he could become parranoid about everything around him being a threat, he could see hallucinations and just generally prang to everything.
Ego is the aspect that holds these two together in a comfortable balance. The Ego could be like the leader of the demons, wanting to restore order to the people around him by silencing anyone who has sinned, which i might add is about 99% of everyone.
The plot could work by the ego wanting to control humanity, but the superego starts to get paranoid and believes the ego wants to destroy him, the Id then goes ahead and kills the kid possessed by the ego causing the Id and superego to cycle out of control. This then leads to a psychotic conflict between the two causing the Id to kill the Superego.
The story would work kind of like the progression of one person into psychosis, shown through the story of 3 possessed teens.
as far as the movie goes, you don't really need any props, jsut have to use your imagination to make the 3 actors/actresses to look like the Id Ego and Superego.