You know, it just occurred to me -- I don't know why it didn't before; maybe you all got this long ago -- that although Jack is usually the comforter, Ennis is usually the protector. He looks up with concern at Jack riding the mountain under a storm cloud, he orders soup, he shoots an elk, he worries about Earl's fate befalling them (and possibly more so Jack, judging from the ominous symbols in the dead sheep/naked laundry scene), he regrets that in the end he wasn't there to save Jack.
All that suggests to me that neither the punch nor his Mexico threat are deliberate and/or sincere.
I have felt for awhile that Ennis' threats or reactions were not deliberate. IMO, that is how Ennis handles his emotions ... by deflecting the situation off onto someone else or lashing out physically. Your first paragraph triggered a thought, however … I have seen Jack as the comforter, more in touch with his feelings, a dreamer, ready to take the plunge and make a life with Ennis. Honestly, I never saw Ennis in terms of “a protector” … but from what you have said, I think that is true. Conversely, there are times when Ennis is
also the comforter, the one who takes the initiative. Think about the reunion kiss; the arm around Jack after Jack’s confessing that he misses Ennis so much he can hardly stand it; the dozy embrace. Furthermore, it is Ennis who breaks down in tears … partially because he can no longer contain his feelings and partially, IMO, because he can’t imagine his life without Jack (as when he breaks down post mountain and at the lake scene). Jack only cries once … and then quickly squelches his tears and drives to Mexico. So, it is not just Ennis who holds back his feelings. Jack does it, too … but in a different way. Jack gets frustrated and meets his needs sexually, physically. Ennis, however, is the only one who can meet Jack’s emotional needs.
Interestingly, neither one can be placed in a single category because they are like real humans … complex. For me, I have often looked at Ennis as the one who did not understand that he loved Jack until it was too late. I may have to reconsider that POV… both Ennis
and Jack never used the word “love” to each other. Although Jack was gregarious with Ennis, he really wasn’t that way without him. Examples … Lureen approaching Jack at the bar and Jack looking rather embarrassed, shy; rarely (if ever) standing up to Lureen or her dad (until the Thanksgiving scene, that is); Randall taking the initiative after the benefit; et.al).
Hmmm … do I need to re-think my entire POV? Maybe … to some degree.