This is my first time writing for Rise of the Guardians, but this moment just struck me so strongly, I had to write something for it. Please tell me how I went!
Even after Jamie says his name and sees him, some part of Jack still doesn't believe it. After so long, and his hopes being torn down so many times, he can't bring himself to believe that it's finally over.
Three hundred years is a long time to be alone, and Jack has not forgotten - will never forget - the feeling of someone walking right through him. It's a horrible, gut wrenching pain, tearing through him, and leaving him feeling sick to his stomach. After three hundred years of having people, flesh and blood people who he knows should be able to touch him, walk right through him, he won't forget what that feels like. Even someone finally seeing him is not enough to dispel that feeling.
Until the moment Jamie hugs him. It's a simple gesture, but to Jack, it means so much. It means that finally, after three hundred years of loneliness, there is someone who can touch him, feel him, believe in him. That's when it finally sinks in. Someone believes in him. The loneliness - is over.