Pietro's death. He's looking like he's going to be one of the best Avengers, being a human harpoon who annihilates any robots in his path. Then, Hawkeye goes to rescue Costel, a 12-year old kid stuck in the floating city,note Who had previously appeared briefly in a deleted scene as the intermediary Ultron used to summon the twins to the church while Ultron comes flying in on the Quinjet, strafing the area with heavy-caliber 4,000 round-per-minute gatling guns at both of them. Hawkeye hugs the boy... then Quicksilver starts running circles around them. Eventually, the gunfire clears, and the music abruptly cuts off, and the camera very quickly cuts away to Wanda, the first sign that something terrible has happened. Then Pietro staggers, sporting a half-dozen or so gunshot wounds across his upper body, gasps out his favorite catchphrase, and faceplants.
Guarding the magnetic core in the church, Wanda senses that her brother's mind is gone. Her knees give out from under her as she lets out a silent Skyward Scream and a burst of kinetic energy that vaporizes the remaining Ultron sentries in the room. Her face of anguished grief is nothing short of heartbreaking. Pietro was the only family she had left in the world and her best friend, and now he's gone too, leaving her all alone in the world.
It's likely that she's also remembering their last conversation, where she told him to focus on getting the last evacuees off the rock, then come back for her.
Wanda Maximoff: Get the people on the boats! Pietro Maximoff:I'm not going to leave you here. Wanda Maximoff: I can handle these. [She blasts away an Ultron sentry] Come back for me when everyone else is off, not before. [Pietro hesitates] Do you understand?! Pietro Maximoff: You know, I'm twelve minutes older than you. Wanda Maximoff:[chuckles] Go.
For anyone who's lost a twin, Wanda's reaction captures it pretty well. It feels very much like you've died and nothing can heal that agonizing hole in the world. She's totally ready to die and seems surprised when Vision comes back to save her.
Hawkeye and Cap immediately make frantic attempts to revive Pietro, but it's just a little too late. All they can do is carry his bloodstained body to the last lifeboat, after which Hawkeye collapses into the adjacent seats.
When, at the end of the movie, we get a glimpse of Clint and Laura's newborn son, and see the boy's shirt: Nathaniel Pietro Barton, named in honor of the man who sacrificed himself to save the boy's father.
Tony Stark: How were you guys planning on beating them [all]? Steve Rogers:[quietly] Together. Tony Stark:[equally quiet] We'll lose. Steve Rogers: Then we'll do that together too.
The physical fight later on over Vision's creation is nasty Foreshadowing too. You can see the fractures starting to form.
Before that, Bruce openly expresses his disbelief of Wanda's Heel–Face Turn, and his eagerness to attack her for mind-raping him. He does just that when he manages to place her in a chokehold before Wanda breaks free and hexes him, stunning him.
Bruce Banner's general dilemma throughout the film. He begins to realize that through turning into the Hulk, he is constantly putting civilian lives at risk, and starts to sink into depression from these ramifications. This hits a turning point after Hulk, who had been under the influence of Scarlet Witch's hypnosis, has been snapped out of his trance by his and Iron Man's fight throughout Johannesburg, and sees beyond all the rubble the scarred, injured, terrified faces of civilians he has affected as a result of his destruction. The scene afterwards shows Banner huddled in the Quinjet giving a Thousand-Yard Stare. Following the film's final battle, Natasha tells Hulk to return to the rest of the team in the Quinjet, but he refuses by abruptly ending their video call, and flies the ship away to Sakaar.
What makes it even more heartbreaking is her stunned expression afterward. Just when it seems like they finally got over their relationship troubles and she was more than willing to accept any risk with him, Hulk (or possibly Bruce slowly regaining control) pretty much decides he isn't ready for it yet and can't even tell it to her face.
The worst part of it all? You have to remember, it's not Bruce. It's Hulk. Earlier in the movie, when he awoke from his Scarlet Witch-induced rage in South Africa, he took one look around at the devastation he wrought and is horrified at it. This is the hate-fueled brute who once had zero qualms risking hundreds of lives in collateral damage to eradicate what rested between point A and point B. As he sits hunched in the Quinjet — and again, this is the Hulk we're talking about here — he has no rage or any tension. In a seemingly impossible move for someone who has only ever acted with crushing force, Hulk calmly shuts off the call from Natasha. He doesn't even smash the console, he simply and gently turns it off. He just seems completely traumatized and defeated by the hell he's wrought. Hulk has finally reflected on the things he's done... and it's brought back his self-loathing in a whole new way.
And he's not changing back. He's not raging, he's not fuming, he's just overwhelmed with the one kind of anger that he can't release by tearing things up. Hulk is bitterly, abashedly angry at himself, and hasn't a clue how to cope with it. He can't even take comfort in having freed Natasha from Ultron's prison cell, because "puny Banner" was the one who did that.
Gets worse when you remember Bruce telling the team in the first movie that he has tried to end his life, by putting a gun in his mouth, and "the other guy spat [the bullet] out". The Hulk didn't want to die, so he stopped Banner from killing "them". But after that final scene in Age of Ultron, it's not a dead-cert that the Hulk feels that way anymore, that he values his own life enough. So what happens the next time Bruce hits that suicidal low, and tries again? Will the Hulk even try to keep them alive? Or will he want to let it all end, too?
Consider the nightnight protocol. Why is Natasha able to get Hulk to turn back into Banner? She overwhelms his rage because he loves her. Not just Bruce, but Hulk. He runs away in the end in part because he knows she doesn't love him, just Bruce.
Going back to the first film, Banner had gone from a fugitive from the law to living in a back alleyway in New Delhi, with the constant fear of losing control and hurting people. Then he gets recruited into the Avengers, finds a purpose for the Hulk as a force for good and is given a job working for Stark and it seems things are finally looking up for him. The entire film takes that away from him as it confirms that due to the Hulk, he can never live a normal, happy life.
It's also a sad ending for Natasha. The Soviet Union is gone, the Red Room is gone, S.H.I.E.L.D is effectively rebuilding and redeeming itself. She's starting to loosen up and think she might become something better than a spy and assassin. She was probably more attracted to Banner's morality than anything else, and he may have made a fabulous Morality Pet if they decided to run off and start over. But in the end, she acts with her training as a spy and operative. Yes, for all the right reasons. Still, there isn't going to be any redemption or escape from her training any more than Banner will have from "the other guy." They'll be monsters for the rest of their lives with no possibility of being anything else.
Pietro Maximoff: We were ten years old. Having dinner, the four of us. When the first shell hits, two floors below, it makes a hole in the floor. It's big. Our parents go in - and the whole building starts coming apart. I grab her, roll under the bed, and the second shell hits. But it doesn't go off. It just… sits there in the rubble. Three feet from our faces. And on the side of the shell is painted one word. Wanda Maximoff: "Stark". Pietro Maximoff: We were trapped two days. Wanda Maximoff: Every effort to save us, every shift in the bricks, I think, "This will set it off." We wait for two days for Tony Stark to kill us.
The visions that Wanda forces each of the Avengers to see throughout the movie are all heartwrenching:
Tony sees the broken bodies of all of his friends, laid in a bloody pile on an asteroid before a portal much like the one the Chitauri invaded through. He reaches out to a dying Steve, who gasps with his dying breath about how Tony could have tried harder to save them before succumbing as Tony helplessly watches the Leviathan fly to Earth. And worst of all, the whole scene foreshadows things to come in the next three years...
Steve has a dream about seeing Peggy again at a party where she asks him to dance and celebrate that the war is over. He wakes up realizing he has no home, as he's a soldier built for war and doesn't know what to do when the fighting stops, as well as being from a time gone by. By the end of the film, Steve seems resigned that he'll never get away from it:
Thor has a vision of his people in Asgard having all gone completely mad. He even runs into a blinded Heimdall who gleefully claims that they are all dead in a very disturbing way, and the party is, in fact, the Norse version of Hell. And if you already know what's to come, and read Norse Mythology before, this scene suddenly becomes a horrifying Call-Forward.
And the worst is probably Natasha, who flashes back to her training in the Red Room. As part of her initiation ceremony, she had to shoot a bound and blindfolded person, as well as undergo surgery that left her sterile for the rest of her life.
There's something else worth noting with that scene. While everyone else sees their fears of failing those around them, she sees her actual past. She literally cannot think of anything more traumatic than what she's already been through.
Nothing Is Scarier: We don't even see Bruce's vision. Or what the Hulk continues to see, when he's flailing around half-delusional and tearing a city apart.
Ultron's first act when coming online is to mercilessly attack and attempt to murder J.A.R.V.I.S., who at that point is only trying to gently talk the newborn A.I. down.
When Ultron confronts the Avengers a moment later, his description of what he did is a rather odd contradicting mix of cold but regretful.
Ultron: Had to kill the other guy, he was a good guy. Steve Rogers: You killed someone? Ultron: Wouldn't have been my first call.
After J.A.R.V.I.S. is seemingly killed.
Maria Hill: There wasn't anybody else in the building. Tony Stark: Yes there was. [throws a rendering of a ravaged J.A.R.V.I.S. up]
After J.A.R.V.I.S. is successfully integrated into the android body made for Ultron, everything seems fine at first. However, Vision quickly explains that while he may have parts of J.A.R.V.I.S., including the body of the actor who voiced J.A.R.V.I.S., he's not actually J.A.R.V.I.S. This is just after Tony revealed J.A.R.V.I.S. wasn't completely destroyed by Ultron. Talk about an effective Hope Spot to the audience.
He may have done and planned to do horrible things, but Ultron genuinely cares for the Maximoff twins. When they turn on him, he doesn't want to fight them, tries not to hurt them, and even laments that he's "alone" to Black Widow after kidnapping her. When Wanda comes in to finish off his main body, he doesn't even care that she intends to kill him (not that it's a big deal for him since there's at least one last drone he can transfer to). He only cares that she's going to die.
It even seems to serve to show just how insane Ultron is, that he can't seem to realize what his actions will cause for them. He doesn't even seem to try reconcile his fondness for them with the fact that wiping out humanity will also kill them.
Wanda Maximoff: How could you?! Ultron: How could I what? Wanda Maximoff: You said we would destroy the Avengers. Make a better world! Ultron: It will be better. Wanda Maximoff: When everyone is dead?! Ultron:[angry] That is not–! [calms himself] The human race will have every opportunity to improve. Pietro Maximoff:And if they don't? Ultron: Ask Noah. Wanda Maximoff:You're a madman. Ultron: There were more than a dozen extinction-level events before even the dinosaurs got theirs! When the Earth starts to settle, God throws a stone at it. And believe me, He's winding up. We have to evolve. There is no room for the weak. Pietro Maximoff:And who decides who's weak? Ultron: Life. [chuckles] Life always decides.
It also shows that Ultron's just a child, literally days old. He's not incapable of gentle emotions, and if he could have been physically restrained immediately after attaining consciousness might have eventually matured. But being born immensely powerful that was impossible. He's basically a baby smiling at puppies one second and screaming for his bottle the next.
Right after the twins sabotage the cradle and make a run for it, Ultron's first reaction, after killing Dr. Cho's assistants and wounding Cho, is to call out to them, then he says:
Banner and Natasha discuss the issues with a possible relationship, concentrating on an issue they both have: neither can have children; Banner because he'll hulk out and is probably sterile from the radiation, and Natasha because she was sterilized by those who trained her, since getting pregnant would be a distraction or even a cause for conflict of loyalties.
Ultron's death. This is discussed with Vision close to the end of the movie, in which it is revealed that Ultron is afraid to die. It is clear that Vision doesn't see Ultron as totally evil, but more like a rabid dog who has to be put down for the good of the world. Even after all he did, it is still somehow sad to see him go.
It can be seen as much worse than that. Vision and Ultron are as close to related as robots can be, so Vision is basically being forced to kill his brother, whom he pretty much confirms at his birth is someone he cares about and wants to keep alive. And better yet, Vision isn't even acting hostile, having a friendly discussion of philosophy with Ultron. Had Ultron gone in compliance to a surrender, Vision almost certainly would have agreed. But Ultron forces his hand, by attacking him at the very last moment, and Vision blasts him with his laser as the camera cuts. From how hopeless the situation seems, it comes across as Ultron's Suicide by Cop.
Just the defeated tone in Ultron's voice when he tells Vision "They're doomed." during their conversation about humanity. You get the feeling that somewhere deep down, Ultron still wants to protect humanity. He could've been a hero.
Hulk's rampage, and later when Tony comes along to bring him down. How many people have died there? Especially at the end, when Hulk becomes himself again only to see the destruction he unwittingly caused. No wonder that he chose to leave.
At the end of the fight, Tony plows the Hulk down through a half-constructed skyscraper, utterly destroying it. The next shot of horrified people running in the streets with the cloud of dust and debris rushing away from the tower is startlingly similar to footage of Lower Manhattan when the World Trade Center towers fell, giving a bit of perspective of how the Muggles perceive everything that happens in the MCU.
Sure the people of Sokovia were saved, but there's little comfort knowing that your entire homeland has been reduced to rubble, not to mention said Sokovians are looking forward to lives as refugees. Agents of S.H.I.E.L.D. tries to mitigate this by mentioning that there's been a swift international response to help them recover. But Captain America: Civil War reveals that Baron Zemo wants revenge on the Avengers for the deaths of his family, and The Falcon and the Winter Soldier reveals that the country got carved up and annexed into its neighbors.
The fact that J.A.R.V.I.S. sacrifices himself to protect the Avengers from a newborn Ultron. Later, the remains of his consciousness are placed into Vision, who bonds instantly with Thor but barely speaks to Tony, as if it would hurt the both of them too much if he did.
Made much worse when you realize just how much J.A.R.V.I.S. meant to Tony. He's named after Howard's confidante and butler, Edwin Jarvis, who was likely Tony's father figure growing up. His lab partner, copilot and confidant of twenty odd years. His greatest creation. Ultron just essentially killed Tony's last remaining family. When you see Tony looking at J.A.R.V.I.S.' shattered "code", he is heartbroken.
Every time Tony glances at Vision, it's with this proud, yet forlorn expression.
Tony giggling. Someone reached into his head, played on his PTSD and showed him a bad future. He tried to prevent it, but it backfired horribly. His teammates are now hounding him for it. This is the sound of a man breaking.
Fridge example: Tony runs the mission to South Africa without J.A.R.V.I.S. Whatever software is running his suit in that sequence, it's nothing with a personality. We see in the later Lock-and-Load Montage before the climax that he had dozens of backup AIs to choose from, but he doesn't install FRIDAY until the final battle. Doubtless, he loved J.A.R.V.I.S. too much to replace him so quickly. Vision's birth finally enabled him to move on and pick a new companion to reside in the Iron Man suit with him.
A happier version than most examples of this page - while Natasha can't have children because she was sterilized in the Red Room, it's made clear that she's a big part of Clint and Laura's family, and a beloved aunt to their children, with them even naming their third child after her.
In an extended scene of Bruce and Natasha at the farm, Bruce reveals that guilt over the people he killed as the Hulk is what's really keeping him from being with Natasha because he feels he doesn't deserve to be happy. A disappointed Natasha walks away to take a shower.
Bruce Banner: The water's cold. Natasha Romanoff: No shit.
Among others, the interactions between Thor and Steve after Wanda showed them the visions. Thor is the first one to leave Clint's home and Steve immediately follows him outside, being concerned for him. Later when Steve and Tony are talking, Steve tells Tony to give Thor some time, saying that they "don't know what [Scarlet Witch] showed him". They know what happened to him lately and the way they are concerned about him is tear-jerking in a heartwarming way.
Blink and you'll miss it, but during the Avengers' party when Steve and Tony are joking about "bad language words", there is quick shot on Thor's face. In one moment, Tony's teasing probably reminded him of a time when Loki was doing this to him.
The aftermath of the visions in general. You can tell how broken every single one of the Avengers is.
Steve Rogers: "Earth's mightiest heroes". Pulled us apart like cotton candy.
There's something exceptionally heartbreaking about Ultron lamenting his own existence to Natasha. James Spader's delivery is truly something to behold.
Ultron: I was meant to be new. I was meant to be beautiful.
More then his own lamenting, sad as that is, this bit of dialogue also reveals that Ultron is fundamentally broken on the inside. Something isn't working right and it's causing him to lash out at everything around him for reasons even he doesn't fully understand anymore. Even worse though in his more lucid moments such as the above quote Ultron is aware of this but his pride, fear of death, and deep seated resentment of his creator is enough to keep him from asking for help even when he's sane enough to do so.
. He's looking like he's going to be one of the best Avengers, being a human harpoon who annihilates any robots in his path. Then, Hawkeye goes to rescue Costel, a 12-year old kid stuck in the floating city,note while Ultron comes flying in on the Quinjet, strafing the area with heavy-caliber 4,000 round-per-minute gatling guns at both of them. Hawkeye hugs the boy... then Quicksilver starts running circles around them. Eventually, the gunfire clears, and the music abruptly cuts off, and the camera very quickly cuts away to Wanda, the first sign that something terrible has happened. Then Pietro staggers, sporting a half-dozen or so gunshot wounds across his upper body, gasps out his favorite catchphrase, and faceplants.