This was going to be a reply to a Tumblr post, but it got really obnoxiously long, so I'm breaking in this new Dreamwidth.
With all the speculation over characters dying in Infinity War, and most of it being about IF characters die rather than HOW, I started thinking about what would make each character's death resonate for me, as a completion of an arc that started early in the MCU.
This post is pretty much just going to cover phase one characters. And blanket content warning for mentions of canonical death wishes and suicidal ideation, as well as, obviously, discussions of how to most impactfully kill a bunch of characters we all really like.
Tony Stark has had a pretty clear arc over the Iron Man movies, and a different, but overlapping, arc in the Avengers ones. IM1 had him realizing his weapons creation was a force for bad in the world and he could do good instead; IM2 was teaching him he was part of a bigger world and he couldn't do it alone; IM3 was understanding that Iron Man (as concept but embodied by Tony) couldn't protect the world from everything. A1 was proving Steve wrong that he could be self-sacrificing; A2 was essentially reiterating the point of IM3 but with a Hulkbuster. (I would guess that the thing from A2 that's most important to remember is Tony's fear at the beginning, that everyone around would die and he'd be powerless to stop it.
So I feel like Tony's best arc would be the one that I've been hoping Avengers 3 and 4 cover, which is that basically every phase-one Avenger dies in A3 and Tony survives, but deals with it, works to make things better, and ultimately ends up sacrificing himself to bring the other Avengers back. This calls back to his willingness to sacrifice in A1, shows that he's confronted and moved past the fear of A2, shows his understanding that he needs a team from IM2, allows him to be the hero rather than the villain he was concerned about in IM1, and shows he recognizes that the world will ultimately be okay without him to protect it from IM3.
Steve Rogers is, I figure, probably the most obvious character to kill off, because, looking at the comics, we have two very ready replacements for him who've already been introduced, and also because, extratextually, CEvans has been pretty clear about not returning after A4, while Mackie and SebStan both have plenty of movies left in their contracts. (I will be ignoring all of that for this post. Besides, it's not about who's most LIKELY to die, it's how their theoretical death could be meaningful.)
Steve's storyline is always going to be what was discussed in Cap1: "Not a perfect soldier, but a good man." Steve was never at risk of being a perfect soldier (although shoddy characterization often paints him that way); his film storylines, at their hearts, have always dealt with either being a good person who prioritizes his principles, or dealing with being a man out of time and adjusting to how his belief system intersects with, or fails to intersect with, the mores surrounding him. His stories also deal explicitly with loss, and what he gave up (his body; his time; the Howling Commandos; his best girl and his best friend) and what he's gotten in exchange (a new body; a new era; the Avengers; Sam and Nat and this new version of Bucky). And on top of that, there's the question of Captain America as a figurehead, at once part of Steve and wholly detached from Steve.
One thing that I find interesting about Steve's arcs to date is that he's never really had to deal with making the wrong choices. He's had to make hard choices, they've carried huge consequences both for him and for those around him, but he's never been thoroughly WRONG. So one thing that could happen would be Steve being wrong, which I think Steve HIMSELF would actually handle a lot better than those around him. I think Steve being wrong, in a lasting way that impacts how people view Captain America The Figurehead, could be a more impactful legacy than Steve himself dying.
(But this post is not about that, and I'm talking around killing off Steve Rogers.)
I also feel like I can't talk about killing off Steve Rogers without acknowledging how much he flirts with death. Whether or not he has a death wish (I know there's lots of meta on both sides), it changes how his death would be narratively satisfying. Is death the ending that he's been looking for, an escape from the modern world, and thus a reward? Or would Steve's narrative arc need to conclude with him wanting to live, and as a result, any death would be inherently devastating, because it could only come after he's decided it's not what he wants anymore?
I almost feel like, while most characters' deaths would be most resonant if they're in big heroic moments, Steve's would be best if it's quiet, and very much not Captain America, and therefore all the more Steve Rogers. For maximum impact it has to be the end of the skinny kid from Brooklyn's arc, and him being Captain America would just be almost a side note. Steve's DONE the big gestures, and we've seen them; in almost every movie, there's a heart-stopping Captain America Saves the Day moment. But we don't have a lot of Steve saving the day.
Or, rather, we do- I feel like I'm negating Steve as individual, and that's not my intent. But the cowl and the shield mean something to people inside the MCU, and even when it's Steve speaking, they hear it as being from Captain America. Steve's always been a hero, even pre-serum, but his heroism is seen as a function of Captain America. We see this in Cap1 when people (besides Erskine, Bucky and Peggy) only take him seriously post-serum; we see it in Avengers during his and Tony's fight; we see it in all the moments where Steve and his shield are synonymous. (Him having a new shield from Wakanda, one without the stars and stripes, along with the logo he tore off his uniform because he's that fucking extra, will already begin to present an interesting break between Steve and Cap iconography.)
So if Steve has to die, the more his death is undeniably Steve, divorced from Cap as iconic figure, the more it completes a really interesting arc about what Captain America is as a role, and who Steve Rogers is as a person.
Thor is an interesting situation because he's had a really great arc in his three movies (from unworthy of his hammer and of his people in Thor1 and earning that back, to showing how he's worthy but choosing not to take the throne in Thor2, and finally accepting the mantle in Thor3), while the Avengers movies haven't really given him an arc at all. Like, I'm not sure what his Avengers arc is that could come to a close, because Joss mostly used him as a Shakespearean Exposition Machine.
I feel like for Thor to die for earth would be a cop-out; it would need to be in service of protecting Asgard. Helpfully, as of Thor3 Asgard is on a spaceship hurtling TOWARDS earth, so it's one and the same. But Thor's death would still need to serve the people of Asgard, not just as a broad theoretical "Asgard is its people" but concretely.
Except Thor dying just leaves Asgard vulnerable, unless he's already done the work to set them up to be safe. But that would mean that someone else (probably Heimdall or Val or Sif, since everyone else is dead) would have to take up the mantle of protector of Asgard. And that's a satisfying start to any of their arcs (fingers crossed for Val!), but not a particularly satisfying end for Thor.
Which brings us to Loki, because I'm not sure how to separate the two, and honestly, I'm not sure how this one would work. Thor and Loki's arcs are so intertwined that for either of them to be satisfying, they need to involve each of them recognizing and protecting the other. So either Thor sacrifices himself to save Loki, and then Loki saves the world in his name with the skills he's learned from years of being around him, or vice versa. But in that case, either one of their deaths would be furthering the other's arc, rather than furthering their own arc, right?
Loki saving Earth and Asgard after trying to take over Earth in A1 and not doing particularly much to take care of Asgard while ruling it has a nice full-circle aspect, and I think that's why people are assuming he'll be the one to die. It would be pretty easy for them to close out his arc like that, and claim that it's redemption (although whether Loki himself ever thought he needed redemption is an open question, and if he didn't think that it's not actually that satisfying an ending for his story).
But narratively, I feel like Loki has more places to go than Thor does. (Or rather: I feel like Loki has more places to go that filmmakers would go to than Thor does. A competent king, like a happy relationship, seems to elude creators; "making good things better" seems like it's considered less of an interesting story than "making bad things suck less.") Which brings me back to the question of how could Thor die, in such a way that it would be rewarding to viewers who love Thor and want to see Thor's storyline reach a satisfying ending.
The questions that Thor3 opens up for Thor are all possibilities: he could move Asgard, he could start something with Val, he could be a great king. But nothing feels unsettled, exactly. There's nothing that's waiting for Thor to do, so that he can grow into the person he needs to be. He's done that growth. And we already know he's willing to die for Asgard, so him actually dying for Asgard only proves he's as good as his word- which the movies have already proven him to be.
A satisfying Thor death would have to be for Asgard. But I can't think of how they could do that in a way that him living wouldn't better serve.
Bruce Banner is a weird case, because we DO know he was actively suicidal at one point, and that because of the Hulk he was unable to kill himself. So death would theoretically mean separating out Bruce from the Hulk, which is in and of itself a fulfillment of one of Bruce's biggest goals since the solo movie where he wasn't Mark Ruffalo.
(To be clear, because Ruffalo has talked about how in lieu of another Hulk movie his ideal Bruce-and-Hulk storyline is playing out over Thor3, Avengers3, and Avengers4, I don't think he's dying in this movie, so this is all a hypothetical. BUT STILL.)
That arc that Ruffalo was talking about is clearly about how much of Hulk is Banner, and how much of Banner is Hulk. What happens to Hulk when Banner's in control, and vice versa? None of these questions, obviously, can be answered with his death. But his death could nonetheless be fulfilling for the audience if his death is part of, essentially, a détente between Banner and the Hulk- if his death is heroic in a way that's not smashing.
Because Hulk can't die, then, the death has to be Banner's, and it has to be Bruce negotiating with the Hulk and the Hulk standing down because of what Bruce says. In other words, it's both Bruce AND Hulk making the ultimate sacrifice, not because Bruce wants to die, but because Banner and Hulk both want to be do the right thing. Hulk's instinct is to smash; Banner's instinct is to hide. For both of them to choose heroism instead would be a pretty huge statement.
Of course, we also need to factor in that part of Hulk has always been- even if it hasn't been explicit in the films, it's been a definite undercurrent- the desire to protect Bruce from whatever's going on outside of himself. Bruce doesn't recognize that, and would need to; we'd essentially need to see Bruce recognizing the Hulk's humanity, and the Hulk recognizing his OWN humanity but still being willing to stand down.
A Bruce/Hulk death I think is really difficult to play, because Bruce was suicidal and as a result that has to hang over the whole possibility. Marvel, obviously, does not want to endorse that, or act like death is an inevitable end to suicidal ideation- which is another reason I think Bruce's death is unlikely- but on the other hand, the mortality rate of human beings is eventually 100%. And Marvel remembering that he was ever suicidal is kind of up in the air anyway.
For Bruce's death to be most impactful, though, I think that it can't just be through his use of science. Science is the area where Bruce feels safe; when he's in danger, Hulk takes over. It would need to be an area of Bruce's life where he's very specifically out of his comfort zone, but choosing to embrace it anyway. But the problem here is that the canon we have of the Hulk thus far hasn't actually given us an idea of what Bruce IS, beyond nervous and science-y and often on the run. So obviously, he would need to make the choice to stay despite that. But for it to be that character moment- what is it about Bruce that would work?
Clint Barton probably has the least likelihood to die in A3, given how little he's in the promotional materials. But even if not for that, they have given Jeremy Renner so little to do over the past several years that I'm not sure what they could do here.
He had a few minutes in Thor, where we learned that he's a good shot. He was under Loki's influence during most of A1, and after that was mostly him trying to make amends. He didn't show up in Phase 2 until Ultron attacked, when the main thing we learned about him was that he had a wife and kids. And in Civil War, he came in to rescue Wanda and ended up in sea prison.
So, like, priority-wise, we know that Clint wants to protect people, especially his family and anyone he sees as young and vulnerable. (Arguably this extends to Natasha, depending on when she was recruited, but we've definitely seen it with his kids and with Wanda and Pietro, and that was definitely an intentional parallel in A2, even if I don't think it worked.) And we know that he wants to atone for the events of A1, even if that really wasn't his fault.
So a death in the name of protecting people would absolutely fit in with what we know about Clint so far. But that's not the same as furthering his arc. And that's honestly because I'm not sure what arc he's had?
We've seen him in different circumstances. We've gained more information about him. But we haven't actually seen him develop. Every arc that I can think of having discussed is more fanon than canon.
Similarly, we saw in A2 that he missed his family, and in Cap3 that he’d "retired," but we didn't actually have an arc of that. We don't know how long he wanted to, or what retirement would mean for him; we don't know if it would be more fulfilling of his ideals to actually retire and get away from the superhero life, or to get back in the game and acknowledge that he never really wanted to retire anyway. They have every possibility for where they could take Clint in these movies, but that's a flaw, not a feature, of the writing thus far.
So I ultimately can't think of anything they could do with Clint that would fulfill his arc, because that would require him having HAD an arc. That doesn't mean they wouldn't kill him, but does take away the meaning from his death; aside from the impact on fans who've projected a lot onto him despite the text's absence, I'm not sure what narrative purpose it would serve in the film.
Which is pretty damning of the franchise, if not an answer to the question I was searching for.
And finally, Natasha Romanoff. She's what started this, obviously- me being all "I am totally chill about anything that they decide to do in Infinity War" and then being like "but what if Nat dies" and realizing I would not be chill with that at all unless it's a satisfying completion of her arc. So naturally I dealt with everyone else first- because of course. This is, for me, the hard one.
She doesn't have a problem self-sacrificing, so her giving her life to defeat Thanos in and of itself wouldn't be a character moment, while it would be a surprising moment for the audience, particularly with rumors of a Black Widow movie finally happening. To deal with my own hypocrisy, I had to figure out what would make a Natasha death complete the arc she's had thus far, in such a way that I'd be, well, not happy with her dying. But at least okay with it.
Natasha has spent the MCU to date struggling with what it means to be a hero, to other people and to herself. She's searching for a kind of redemption, as we see both in her "red in my ledger" comments in A1 and in her wanting Steve to trust her in Cap2, but it's not a way to make up for her sins, which she doesn't think she can do; her goal is to be the kind of person people around her seem to be. She sees herself as a monster (A2) and is surprised when other people don't; she is willing to sacrifice to have a team/family (Cap3) and ends up playing into exactly the stereotypes people believe about her- her willingness to betray anyone- as she attempts to keep them together.
A satisfying conclusion to her arc would either need to offer her some kind of sign that she's considered unequivocally "good" by someone whose view actually matters narratively (
My feeling has been, and very much remains, that Natasha dying would be a cheat, because Natasha's narrative has always been about consequences. Her heroism in and of itself is a direct consequence of her villainy before, but moreover, her role has consistently been dealing with the annoying fiddly bits of superheroing that no one else wants to do. I mean, the "always cleaning up after you boys" like in A2 was a dumb joke, but it's pretty much what she does; her working with the congressional oversight at the end of Cap2 is the most obvious version of that. But we never actually see her dealing with fallout, and I would love to for once actually see that, and see the toll it takes on Natasha. Because I've never gotten the impression she's particularly good at it, or that she likes it- she's not Pepper Potts and she couldn't be- but dealing with the consequences is often dealing with the gray areas that most characters don't want to think about (see also: Tony starting an entire damn civil war over his sudden realization that conflicts have casualties), and muddling through that gray area is very much her wheelhouse whether she likes it or not.
But in the absence of that, I feel like we should see the other characters dealing with the fallout, and seeing the ways that the absence of Natasha impacts the way things are handled. Who has to do the press conferences? Who handles the paperwork? How much did she do that they took for granted?
So, TL,DR: I don't have any good speculation about who they're actually going to kill. But if any of the phase one Avengers has to die, I hope this is at least part of the decision.