The film K-PAX takes the viewer on a journey to find an answer of our own. The viewer is pulled in the direction of two possibilities, two answers and two completely different ways of watching the film. If you take away all peripheral happenings and meanings of the film, the question left to answer is: Is Prot a psychotic earthman or the alien he claims to be?
In the scene where the psychologist Dr. Powell sees Prot for the first time, the one-way glass makes it so that Dr. Powell can see Prot, but not the opposite. Still, Prot seems to know, or feel, that there is someone behind what he should see as a mirror. The camera angle shows the reflection of Dr. Powell's face directly on top of the picture of Prot's face. Since this happens before they actually meet, I believe it was made in order for the viewer to predict that a connection between the two will develop, or maybe Dr. Powell's meeting with himself and the meaning of his own existence. Later in the film we are taught that Prot can see ultra violet light, an ability no human has. This could mean that Prot has other visual abnormalities as well. Could it be possible that he has the ability to see though one-way glass? Does he see more then the rest of us?
The scene where Prot tells Dr. Powell about the Big Bang and how it all works, is a central statement of the film. The theory we are presented, the directors beliefs, describes our universe as currently expanding, and later shrinking, until it collapses into a new Big Bang. At this point everything will start over again, and everything that happened last time, will happen again. Somehow Prot's sentence from the film; "You'll find yourself back here again in exactly the same place, so you better get it right this time.” makes us think through life and the choices we make. It refers to the importance of every single thing we do, every single day. Even the smallest decisions make a difference. The film asks viewers to look upon his or her life, the world and the importance of one's actions. The film really makes us think about the human being, and if how we act and what we do is correct?
The film describes what would happen if an alien, looking exactly like a human, were to arrive at our planet. Prot appears at a train station claiming he is from another planet, but otherwise sane. He is immediately placed in a psychiatric institution. Is that correct? The director clearly wants us to think about this, what gives the human being the right to act in this way, acting as if there is only that one possibility.
In this film there is no correct answer to the “big question”. Depending on how you approach the film, the answer could be the one, just as well as the other. The films central premiss can be in one of three ways: The option where Prot is an alien from K-PAX, simply visiting earth, or is Prot is an alien, who has taken control of Robert Porter's body. A third option is that Prot is a product of Porter's imagination, his psychosis, that he is a delusional and traumatized person in need of psychological treatment. The film provides evidence that supports all three of these possibilities.
Personally, the second option appeals to me the most. In this theory of the film's truth Prot is an alien from the planet K-PAX, who came during Porter's suicide attempt. He saves Porter's life, but Porter's brain is severely damaged. Prot somehow takes control of Porter's body and mind. Porter is unable to take care for himself, so Prot decides to stay with Porter's body until someone is found to take care of him, and understand his troubled mind. In his search for this caretaker, Prot lets himself be admitted into the Psychiatric Institution of Manhattan, where he meets Dr. Powell, a psychologist who devotes time and effort into finding out what happened to Porter. When he finally learns the truth of Porter's tragedy, he shows great sorrow and compassion for his patient. Prot accepts Dr. Powell as a good caretaker for Porter.
Prot is then able to leave Porter behind and return to K-PAX, together with an other patient, and her body. Prot and Bess travel back to K-PAX, fulfilling his stated plan to leave Porter behind. Prot leaves Porter, returing Porter as the man he was before Prot came, taking his next project, Bess, along for the ride.
This interpretation of the film is based on several events. The first and probably most confirming evidence is the fact that Prot knew the exact physics of his solar system, something no astronomist on earth knows. Another fact that proves that Prot is from K-PAX is that he can detect ultra violet light, something impossible for a human being. The fact that Prot is unresponsive to the drug Thorazine, which is meant to have strong anti-psychotic effects, also supports the view that Prot has been telling the truth all along, and is not delusional. According to this theory Prot is living at the Psychiatric Institution of Manhattan by free will. He could have left at any time, as he does during his journeys “up north”. He let himself be admitted in order to find a caretaker for Porter.