In the original X-Men movie, when Magneto's device
at the end, there is a quick shot of Jean Grey looking sort of stunned as the wave of energy goes through her. No other characters are shown having similar reactions.
When we pick up with Jean and Scott in X-2: X-Men United, Scott and Jean have a conversation about her powers specifically since the Liberty Island incident.
Scott: Jean? You OK?
Jean: Yeah, I'm fine. It's just a headache.
Scott: It's not just a headache, is it? I wasn't sure how to say this, but since Liberty Island you've been...
Scott: You've been different.
Jean: My telepathy's been off lately. I can't focus. I hear everything.
Scott: Jean, it's not just your telepathy. A month ago you had to concentrate just to levitate a book. Now when you have a nightmare the entire bedroom shakes.
Jean: My dreams are getting worse. I keep feeling something terrible's about to happen.
Scott: I would never let anything happen to you.
This, of course, is a foreshadowing of the end of X-2 where
Jean sacrifices herself and we are teased with a vague Phoenix shape in the water in the last frames of the film.
Putting together just these bits, it's not a far stretch to think that Bryan Singer originally intended the energy wave of X-Men to have been some sort of catalyst in the Phoenix Force being drawn to Jean.
Unfortunately, director Bryan Singer abandoned X-Men: The Last Stand early into pre-production and the writing staff changed. In the final version of the third X-Men movie,
the Phoenix is merely a repressed personality of Jean's and not a cosmic force.
In this storyline, to my recollection, it is never stated that the Liberty Island incident helped unlock
the Phoenix personality,
but it is possible.
Has Bryan Singer, or anyone else stated how the Liberty Island incident changed Jean, or how he intended to merge Jean and the Phoenix Force?