@jerottblyth I was writing this in the replies of your “ a glimpse of BJ's post-series white picket fence” and then I got annoyed with the limit, so!

I just rewatched the episode with Hawkeye's ex that he didn't marry (twice), and BJ talks about how he's never even been tempted by another woman, vs later on cheating once (I believe in s5 -- the first BJ episode I really commented on, because it surprised me at the time and I couldn’t place him or it), and then later on him considering leaving Peg for the reporter... 

and then I watched some bits of Inga (s7 -- the last of the relatively what I call “good boy BJ” seasons, and the season that ends on all the main cast family members meeting one another, which idk, I just place at an interesting juncture narratively) in which he talks about himself and Peg as equals/her as a woman who has a mind being a good thing, and how that contrasts with the especially 8-onwards intense reactions he has to her growing into a more and more independent person -- changed beyond the person he knew before he left, changed without him, changed to no longer needing him, changed into a reality he cannot return to and pick up from as if he never even left in the first place (not that I read BJ as conservative for the day technically, but that she’s not the person that said goodbye to him and that manifests in unintentionally sexist ways, where he gets upset by her just living her life, when he needs her to be a symbol of unchanging normality that turns back on the second he’s back in the picture and youknow... that’s fucked up sir)

I think it fits with the weariness of the later seasons: BJ s8-onwards getting more cruel and lashing out more, and him and Hawkeye increasingly acting like an unstable relationship in which Hawkeye often plays the role of the placating wife to an emotionally unpredictable husband. I make it heterosexual on purpose, my headcanons about BJ do veer more towards him having a het read of whatever is going on between him and Hawkeye -- first evidenced that one time he was physically violent, and Hawkeye was both an outlet and a consoling partner and BJ was jealous of not getting to be a partner to Peg/father to Erin, and jealous of Trapper’s relationship to Hawkeye at the same time??? 

Long story short there is a trajectory for sure, from the man who arrives to the guy I’m seeing now (one more episode left before the finale!), and yeah, I definitely like to read it as the fantasy-of-home bit by bit falling to pieces around him, and also the guilt at all of that heroic all-American fantasy of war not being what the reality is, and maybe feeling like an idiot for believing in any of it in the first place (he had that line where he mentioned that he had the chance to not get drafted and he wanted to do the honourable thing, or something along that phrasing, and he has a few episodes in which he does try to play hero of a kind, like in BJ Papa San and he gets very upset when he can’t save the day), and of course the guilt at all of his personal failings, especially -- I decide to headcanon -- the fact that he did cheat. The evil of the situation seeped into him and made him a “lesser” man than what he was 

and all of that manifesting his pettiness (which was clearly something that was already there, although pointed in the direction of acceptable targets like Frank or bad guys of the week, or that old friend he had who was Also A Dick and how that suggests some of BJ’s past, or even Charles, soz Chuck -- because BJ is a Good Guy Honest). 

And now I’m on my rewatch at the same time, and almost finished s4, and looking at it from the pov of that trajectory, it’s very fun looking for early-season-in-hindsight cracks in the “good boy persona”

and with all of that, I do enjoy currently joking about how he’s the end-series villain (Frank is gone, Charles isn’t the main source of conflict, Margaret has long since developed into the love of my life...) but the most interesting thing about it is of course that the story doesn’t end with a villain, it just ends with broken people, from what I see -- BJ is not a bad guy, certainly not in comparison to the likes of someone like Frank, he’s just... not coping at all. And some of the things he does are seriously messed up, and I wouldn’t be surprised if he does more things like that before the end.......

I do like seeing how different characters break, and BJ’s breaking is oh so very messy/shrapnel filled