Jack as the wind is not only in the movie, but also in the story. I'm sure this has already been mentioned at some point of this 8 pages long thread.
But what stuck me today is how similar Jack enters the scene in both, story and movie.
In the movie, Ennis is already at Aguirre's trailer. Then the wind refreshs and announces Jack's arrival.
In the prologue of the story, it's very similar: Ennis is already in his trailer. And even though Jack is dead at this point, he enters the story with the very first sentence: Ennis Del Mar wakes before five, wind rocking the trailer, hissing in around the aluminum door and window frames.
The next sentence even emphasizes his presence: The shirts hanging on a nail shudder slightly in the draft.
Jack is there, is with Ennis and is in the story even before he is introduced to the reader by name.
Somehow I find this thought oddly comforting: Wyoming is a very windy edge of the world. Jack will always be with Ennis.