Spoilers ahead for Episode 21 of Agents of S.H.I.E.L.D. Season 5, called "The Force of Gravity."
Only one episode is left in Agents of S.H.I.E.L.D. Season 5, and there's no guarantee at this point that S.H.I.E.L.D. will get a Season 6. Thanks to the trip to the future that showed the destroyed Earth, Glenn Talbot's recent upgrade to the madman Graviton, and the events of Avengers: Infinity War, the stakes on S.H.I.E.L.D. are higher than ever before, and "The Force of Gravity" may have set the stage for some big deaths in the finale. The episode ended on the reveal that Centipede Serum can be used to save Coulson's life as well as to deliver Odium into Talbot to take him out for good, thus preventing the destruction of Earth and changing the timeline.
Unfortunately, only enough Centipede Serum is left for one of these two options, and Coulson is fading fast. Many of the characters have different motives now that they're facing the end of days, and the finale may play out in a way that somebody (or somebodies) have to die before the very end. Here are the three characters whose deaths would make the most sense for the series at this point.
On the one hand, Coulson is the closest that Agents of S.H.I.E.L.D. has to a lead character, and he's the show's biggest connection to the larger Marvel Cinematic Universe. That said, S.H.I.E.L.D. has been pretty straightforward in setting up his death in Season 5. He made his peace with his impending death after the deal with Ghost Rider, and he refused to agree to May and Daisy trying to find a means of prolonging his life. We can bet that he'll be 100% against using the remaining Centipede Serum to save his own life, especially when the entire world is at stake. Talbot must be stopped before he uses his powers to split the planet apart to get at the gravitonium reserves, and Coulson would certainly give his life to prevent such a thing from happening.
A future version of Coulson didn't have a part to play in the Lighthouse during the first arc of Season 5. Given that Coulson is returning to the MCU movies in the not-too-distant future, maybe the time is right for S.H.I.E.L.D. to kill him off. The show might be ending anyway; why not give Coulson a glorious death? Besides, Coulson got to make out with May, score a big damn hero moment with a shield, and enjoy a few moments of lightness with Daisy. S.H.I.E.L.D. could totally be setting him up to bite the dust.
The agents of S.H.I.E.L.D. may be the good guys, but there's no getting around the fact that killing Talbot at this point may be the only way to guarantee the survival of the planet. Fitz and Simmons devised a way to kill him via Odium and Centipede Serum, and even some of the less quick-to-kill agents are coming around to the idea of taking Talbot out. If things get bad enough in the finale, even Daisy and May could conceivably agree that using the Serum to kill Talbot gets priority over using it to maybe save a Coulson who doesn't want to be saved. Talbot can't be allowed to win, and he might have to die if he's going to lose.
There's always the chance that the good parts of Glenn Talbot are still alive in him underneath all the madness. Nevertheless, if his pal Coulson, his wife, and his beloved son weren't able to bring out those good parts, he may be beyond reaching. The only way to end his story could very well be death. If Coulson dies in the finale, the odds are good that Talbot will die as well. The question is whether Talbot could die without Coulson also dying.
Oh, poor, sweet, silly Deke. Fitzsimmons' grandson has turned out to be a wonderfully endearing character who can deliver comic relief at times when it would be super inappropriate for one of the agents to be cracking jokes, and Jeff Ward has managed to fit into the existing ensemble quite well. Unfortunately, Deke doesn't belong in 2018 with the agents while he's the same age as his grandparents, and he could very well blink out of existence if Fitzsimmons successfully change to timeline and prevent the Earth's destruction.
Fitz was previously convinced that changing the timeline was impossible and thus Deke would not blink out of existence, but "The Force of Gravity" saw him changing his mind. Deke's existence is proof that the terrible timeline is still intact; the only way for S.H.I.E.L.D. to definitively prove that the timeline has been altered may be to get rid of Deke. Oh, poor, sweet Deke.
All of this said, there's one other character whose fate I'm personally worried about:
Every since Simmons declared that she and Fitz were invincible because Deke existed, I've been waiting for the other shoe to drop on Fitz. The show seemed to hint that Fitzsimmons hooked up during one of their brief interludes alone earlier in Season 5, which could have been enough to make a baby. If Simmons is already pregnant, Fitz is very much not invincible. Sure, there are inconsistencies within the timeline that would complicate Fitz biting the dust in the finale, but I'm still worried about the guy. S.H.I.E.L.D. took him to some dark places in Season 5; what if there was never a plan to bring him back?
We'll have to wait and see. The Season 5 finale of Agents of S.H.I.E.L.D. will air on Friday, May 18 at 9 p.m. ET on ABC. Hopefully ABC will announce whether or not S.H.I.E.L.D. will be cancelled before that point since the writers have been preparing to change the finale in the event of a cancellation. For what you can watch once S.H.I.E.L.D. is done for the season, take a look at our summer TV premiere guide.