Natasha greeting Hulk with a warm "Hi, big guy" and using a lullaby to de-Hulk him. Especially heartwarming considering that she used to be scared to death of him in the first Avengers movie.
The Maximoff twins are quite endearing as a pair, even when they're villains. They do look out for each other, no matter which side they're on. Their very first scene is of them holding hands, and while Wanda is usually the one speaking for the two of them, Pietro always supports her, even if it's just through body language. When his attempt to upload himself into the Vision succeeds, Wanda is finally able to read his mind. When she sees all the destruction and annihilation he wants to inflict, she is unsurprisingly horrified and voices as much. Afterwards, an equally upset Pietro is shown hugging her and kissing the side of her head to comfort her.
Bruce and Natasha are more open with each other then anyone else in the film, and the two seem genuinely happy whenever they're together. It just makes Hulk deciding to go off on his own at the end more heartbreaking.
In The Avengers, Natasha was so terrified of the prospect of even being in the same room as Banner/Hulk that Banner acting like he was beginning to rage out immediately sent her scrambling for a gun. Later, when she's assaulted by the Hulk, she ends up a shaking, terrified mess huddled in a corner of the Helicarrier basement. In this movie, she's the only one the Hulk will act positively toward and the only one who can calm him. Imagine having an intense fear of an animal like a tiger or bear, before eventually learning how to handle that animal and be its trainer. Natasha conquers her fear of the Hulk and Bruce, AND the Hulk actually learns to trust her.
Even though it's a Chitauri weapon, and by all rights, Thor is the one who should take the scepter, he gives the duty of retrieving it from Strucker to Steve and Tony, choosing instead to evac a wounded Clint. It just goes to show how much Thor trusts his teammates. Not bad for people who he saw as "petty... and tiny."
Even though the film utterly sinks the Clint/Natasha ship, their relationship is still by far the most affectionate and close-knit of all the characters: openly referring to each other as "my best friend," comforting each other when wounded, even Clint's kids calling Natasha "Auntie Nat." He and Laura even had plans to name their third child after her. The only reason they didn't is because said kid turned out to be a boy, so they name him Nathaniel, after the male form of Natasha's name.
When he breaches the HYDRA fortress, Tony unleashes a barrage of the anti-personnel ammo he carries on his shoulders. But unlike in the first Iron Man movie where he mercilessly slaughters a bunch of Ten Rings terrorists, here he only wounds to incapacitate the HYDRA soldiers, so they can be captured and properly tried for their crimes. Nice to see the so-called Merchant of Death having some Character Development.
Also in the fortress, how genuinely happy Tony sounds when he finds the secret door:
Tony: Please be a secret door, please be a secret door, please be a secret door! Yay!
The Avengers and SHIELD going so far out of their way to save as many civilians as possible throughout the movie. They even acknowledge they are willing to die if they can't save them all. Quicksilver actually does. After Man of Steel and its ridiculously high civilian kill count, it's refreshing to see superheroes actually trying to save lives and succeeding.
A very small moment towards the beginning; when the Avengers are on the jet after the battle, Thor goes over to Loki's staff and touches it almost fondly. It may be a weapon of destruction, but it was once wielded by his brother and is a connection to him all the same.
And the fact that in Thor's vision, Heimdall calls him not just Odin's son, but Odin's first son. No matter what happened between them, as far as Thor and Asgard are concerned, Loki is still part of the family, and some even still remember Hela.
This makes it more poignant when they come to his aid when Ultron has him on the ropes in Seoul, and he's technically the first Avenger to accept them as a part of the team.
When the Avengers throw a party, it is, in the tradition of Hollywood parties, full of attractive extras in snappy outfits ... and a bunch of old, old men wearing their World War II medals. Because Steve has friends too, and he hasn't forgotten them.
Made even better by Thor happily drinking with them and telling stories: he's an Asgardian, after all — if there's one thing his people love, it's listening to old war stories.
Not only that, it's been established that Steve can't get drunk off regular alcohol. Here, he and Thor are shown passing Thor's Asgardian mead back and forth; Thor's happy that he has a worthy drinking partner, Steve's happy he can finally get a buzz. It's a great Friendship Moment.
The men are all Normandy veterans, and proud of what they did, despite all the blood and horror on the beaches. They're also still youthful in heart, which makes one of them decide to take a tiny sip of the terrifyingly strong Asgardian mead Thor brought in.
The fact they're still alive probably means they were teenagers when they enlisted, and would've looked up to Captain America much like the Real Life young patriots his comic title was originally marketed to. Heck, they might have even worked with him. Now, they're partying with the hero they'd thought lost for 70 years.
Also, the fact that Stan Lee’s cameo here is a vet. He really did serve in World War II, albeit as a Signal Corpsman (repairing telegraph poles and other communications equipment).
The party scene in general. The Avengers have friendly banter out on the field, but just seeing them hang out and have fun, and bring all of their friends to join them, is really sweet. When the party dies down and it's just the team, still drinking away and playing party games, it goes up to eleven. The film could have been the opening action scene, and then just a real-time depiction of the party, and it would still be great. A shame that Ultron had to kill the moment.
The 'my girlfriend is better than yours' argument between Tony and Thor is pretty heartwarming; they both just look so damn proud of what Pepper and Jane have achieved.
Considering how Tony and Thor are both of the The Pornomancer variety (out- and in-universe), it is utterly refreshing to have two alpha men measuring their worth not by their own achievements (which are nonetheless considerable), but by how badass their partners are. With neither of them working in a "traditional" feminine field, to boot: one's the CEO of a multinational corporation while the other is a Nobel prize contender for physics.
Steve turning the tables on Nat and encouraging Banner to pursue a relationship with her. He's genuinely happy at the idea of Natasha falling in love, albeit wistfully so, and tells Banner they deserve to be happy.
Steve: As maybe the world's foremost authority on waiting too long... don't. You both deserve a win.
When Ultron gate-crashes their after-party, the Avengers are repeatedly shown covering and protecting Helen, who is the only person present who does not have any combat knowledge whatsoever.
While the team are in South Africa fighting Ultron and the twins, Bruce realizes that something's up and asks them if it's a code green, i.e. if he needs to turn into the Hulk and help them. Bruce hates it whenever he needs to become the Hulk ... but he won't hesitate to do it at a moment's notice in order to save his friends.
During the entire Hulk vs. Hulkbuster fight, Tony is constantly trying to protect civilians and talk down Banner, even as he's trying to tear him apart.
He never stops talking to Bruce like he's a person, calling him by his real name and trying to appeal to his better senses.
The Avengers meet Hawkeye's wife and kids for the first time. Except Natasha, who immediately gets a hug from Clint's young daughter and asks Laura (Clint's wife) how her pregnancy is going.
Lila: Did you bring Auntie Nat? Natasha:[forcing a smile] Why don't you give her a hug and find out? [Lila immediately glomps her]
During their meeting with Fury, Lila goes to show her a picture of a butterfly she drew...and rather than doing the Not Now, Kiddo move like you would expect, Nat actually smiles when she sees it, and strokes her cheek fondly.
When you take into consideration the fact that Natasha can't have kids, the way her face lights up when seeing Clint's come to her is both heartwarming and heartbreaking. This is the closest she will get to having children and she knows it.
Clint's newborn son's middle name is Pietro, in honor of the man who saved his father's life.
Hawkeye's telling his wife about why he is a true companion within the team, as without him or them, it would all fall apart. This showcases Hawkeye's rather Hidden Depths of being the team's heart.
Just the fact that Hawkeye, the team member who's considered The Load by a lot of comicbook fans, is actually the happiest and most fulfilled in his personal life.
The fact that Nick Fury personally made arrangements to keep the family a secret (they were mentioned to not be on SHIELD's files), to protect the Barton family; ol' Nick was looking out for Clint.
Nick Fury showing up in the Bartons' barn and talking to Tony before he talks to everyone else. Specifically him listening to Tony talk about the nightmare vision that Wanda gave him, and offering him a bit of moral support. When he says he's there because he cares about Tony, you almost feel a bit of a fatherly sentiment coming from him. Particularly heartwarming is his statement that Tony is better than he thinks he is and doesn't deserve to be hated for Stark Industries' past as a weapons manufacturer, simply because the world was a really violent place long before he came along.
Nick Fury: You've come up with some pretty impressive inventions, Tony. War isn't one of them.
Better, this little exchange.
Tony: You're not the director of me. Fury: I'm not the director of anybody. I'm just an old man who cares very much about you.
It goes by very quickly, but when Tony is angsting about his vision of destruction, he mentions seeing his friends dead. Friends. Proof that Tony Stark has a heart.
Vision ultimately proving to be what Bruce and Tony originally wanted Ultron to be, albeit with a British accent, cheerfulness, and JARVIS's personality. Shortly after he's 'born' he looks out the window of the Avengers tower at Manhattan below and, where Ultron saw only chaos and destruction, he sees life. Flawed, to be sure, but beautiful and worth saving nevertheless.
Everyone (save for Thor, and to a lesser extent, Tony, Bruce, and maybe Wanda) is skeptical of Vision and suspicious of his intent. That is until he effortlessly hands Thor his hammer. After that, they still don't know exactly what to make of him, but none of them question if he's good or evil.
Vision and Ultron have a brief moment where they casually converse, since they're the closest thing to a family either one has. Of course, they also detest each other, but Ultron technically created Vision.
Earlier in the film, when asked about where his allegiance lies, Vision explains that he does not want to kill Ultron since he is alive and unique, but understands that it must be done because he poses too large a risk to this planet and the people who live on it.
Clint telling Wanda that he doesn't care what she was or did in the past; if she steps out and fights alongside him, she's an Avenger. She does.
Clint Barton: Are you up for this? Are you? Look, I just need to know because the city is flying. Look, okay? The city is flying, we're fighting an army of robots... and I have a bow and arrow, none of this makes sense. But I'm going back out there because it's my job. Okay? And I can't do my job and babysit. It doesn't matter what you did or what you were, if you go out there, you fight and you fight to kill. Stay in here, you're good, I'll send your brother to come find you, but if you walk out of that door... you are an Avenger.
The speech is not a Drill Sergeant Nasty or tough love type of speech. Clint is very understanding of panic and tells Wanda there's no shame in hiding from all this if that's what she wants to do. He even promises to send Pietro to get her if she does. It's nice to see both a demonstration of his status as The Heart. It also serves as a nice callback when you realize that Clint probably gave the same speech to Natasha to convince her to join SHIELD. As she described it back in The Avengers:
"Before I worked for SHIELD, I, uh... Well, I made a name for myself. I have a very specific skill set. I didn't care who I used it for, or on. I got on SHIELD's radar in a bad way. Agent Barton was sent to kill me. He made a different call."
Nick Fury's The Cavalry moment as he literally comes flying in with a Helicarrier to rescue the innocent civilians trapped on Ultron's floating island; it is heartening to see that in spite of spending half a century as a nest inside which the rot of HYDRA bred, S.H.I.E.L.D is still at heart a bastion of heroes who stalwartly defend the innocent and helpless.
Pietro:This is S.H.I.E.L.D.? Captain America: This is what S.H.I.E.L.D. is supposed to be. Pietro:[smiling widely]This is not so bad.
The fact that one member of the crew is Cameron Klein, the guy who refused to launch the Helicarriers in Captain America: The Winter Soldier.
There's also the fact that S.H.I.E.L.D. never directly engages the Ultron drones (except those that are attacking them), instead opting to primarily help with evacuation efforts.
Goes double with knowing Peggy Carter's legacy didn't turn out to be a complete sham after all and may yet become what it was meant to be.
Goes triple after Agents of S.H.I.E.L.D. revealed who was keeping that Helicarrier operational. Cap was unknowingly approving his largest fanboy's work as the new Director of S.H.I.E.L.D.
Just as one of the rescue ships is about to take off, a stray dog hops on board and a police officer takes the time to pat him on the head. Small but sweet.
The fact that a good chunk of the final battle with Ultron is the Avengers—all of them—regularly handing off evacuation duty.
For the villains: Ultron feels a genuine connection to the Maximoffs, and seems to view them as his only allies or even friends. At the climax of the battle, when Wanda confronts Ultron after he murders Pietro, even though it's after they've turned against him, what is the only thing he says?
Ultron: Wanda, if you stay here, you'll die. [Wanda promptly kicks his ass.]
Ultron also asks them to please not fight him after their Heel–Face Turn; he really didn't want to kill them.
It gets to the point of Tear Jerker, because if you listen to Ultron's voice, he sounds less like a friend and more like a concerned father telling his teenaged daughter to get to safety. For someone with such easily pressed Berserk Buttons, it's amazingly touching that he's not even vaguely mad at Wanda, just worried for her.
At the end of the climax, Vision rescues Wanda and they share a brief glance. This, combined with what happens in the finale, seems to help Wanda and enables her to move on from Pietro's death.
The fact that Vision is there at all means he must have realized that Wanda hadn't reached safety like everybody else and went looking for her. And he saved her even before going after the last Ultron drone.
Arguably, she's in an emotionally vulnerable state with her twin having just died, which would explain why she's more open to pursuing a relationship with Vision. A flashback in WandaVision set not too long after the movie shows him being one of the few to give her an outlet to open up about her grief about losing Pietro. By Avengers: Infinity War, they have practically tied the knot.
It isn't Bruce who decides to fly off in the Quinjet, it's the Hulk. When he isn't in the middle of a rampage, even he realizes that he doesn't actually want to hurt anyone.
When the new Avengers line assembles at the end. Just when you think that Vision would have gone off on his own, it's great to see him officially become an Avenger.
After she's shot by Ultron, it's left ambiguous as to what happened to Helen Cho, and it seemed like she bit it, but a brief scene at the film's conclusion reveals she made a full recovery and went right back into medical.
After the mind-control trauma he'd suffered in The Avengers and the mental side-effects he was coping with in Thor: The Dark World, it's nice to see Dr. Selvig finally back to normal.
The small things near the beginning of the film - Tony's "Jarvis is my Co-Pilot" bumper sticker, and their affectionate interactions before the party - that make it clear that Tony loves Jarvis. It makes the AI's apparent death that much more meaningful. Tony's delight at finding Jarvis alive is clearly just as much about having his friend back as it is about a chance to create what Ultron was supposed to be. Considering the Pinocchio motif found in Ultron, it could even be seen as a chance to make Jarvis a real boy!
In a deleted scene, Pietro gives away items he stole using his super-speed to the poorer people of Sokovia, including medicine for an old man who can't afford insurance.
One of the people he gives a gift to is the woman who's seen with the boy Pietro and Hawkeye save at the end at the cost of Pietro's life.
Finally, there's the fact that by the end of the film the team has collectively stopped referring to each other by last name. The first Avengers film showed them becoming a team. Age of Ultronshows that team becoming a family.
despite their still being adversaries at this point.Maria Hill: They were apparently volunteers. It's nuts.