Heartwarming / Harry Potter and the Goblet of Fire
From the Book:
Frank Bryce is an elderly grounderkeeper and war veteran, who doesn't trust the police even when intruders break into the abandoned Riddle House. What makes him decide to trudge to the phone booth and make a call to the cops? Hearing that a boy named Harry Potter is in danger. He doesn't even know that Harry is a famous wizard child or a kind boy; he's a child in danger and needs help. Too bad he gets killed before he can do anything about it.
In Harry Potter and the Goblet of Fire, as the realization of Cedric's death is sinking in, and Harry is surrounded by people but doesn't want to be seen crying (he hasn't truly cried in the books yet, and won't until the sixth):
Mrs. Weasley set the potion down on the bedside cabinet, bent down, and put her arms around Harry. He had no memory of ever being hugged like this, as though by a mother.
Harry: I told him to take the cup with me. (eyes and throat burn)
Likewise, before the 3rd Task, when the family of each Champion are supposed to turn up to support them, and Harry doesn't think anyone would visit him (the Dursleys certainly wouldn't even if it were possible for Muggles to come); Mrs. Weasley and Bill turn up to cheer him on, as if he were their own. Bill also tells Harry that Charlie would've come too if he was able to get time off from work.
The fact that Professor McGonagall doesn't even explain to Harry that it's the Weasleys and Cedric matter-of-factly comes back from the room to tell Harry "they're waiting for you" shows that even they know that the Weasleys are essentially Harry's family.
Also, after being named the Fourth Champion, nearly everyone — including Ron, Harry's best friend — believed that Harry had somehow found a way to sneak into the tournament, just to gain fame. However, the next morning, before demanding answers from Harry or even mentioning the whole fiasco, Hermione brought Harry a piece of toast, knowing he didn't want to eat in the Great Hall with all the attention he was getting, and asked him if he wanted to go for a walk. Harry later told her everything that happened and "to his immense relief, Hermione accepted his story without question," as quoted from the book.
After Harry completes the first task, Ron comes to his senses and tries to apologise for not believing him. Harry tells him "It's fine" and they grin at each other. Cue Hermione bursting into tears.
A rather minor one, but in Goblet of Fire, the fact that Harry takes it upon himself to warn Cedric about the dragons in the First Task to be an immensely heartwarming simple gesture of genuine, selfless decency. It's moments like that just as much as — or more than — the huge battles which make Harry a worthwhile hero.
And Cedric returns the favour by giving Harry a clue about the egg.
Likewise, the conversation leading up to Harry and Cedric grabbing the Cup is among the most heartwarming moments of the series. Cedric, who was so popular during the tournament, giving up glory to Harry, who had been tormented all year long. Harry, who had held a serious grudge against Cedric because of his relationship with Cho, suggesting that they take it together. It was a beautiful moment — and it made what happened next that much more shocking and terrible.
It's even more poignant because, as it's pointed out in the book, Cedric is willingly giving up the kind of glory Hufflepuff hasn't even come close to in decades. As is so often seen in the fandom, Hufflepuff has an (undeserved) reputation as the useless house, the "load o' duffers", the ones who aren't special or important in any way. Cedric knows that. He knows that if he and Harry walk out of the maze both holding the Cup, it won't be Hufflepuff that goes down in history; it will be Harry Potter, once again. He willingly gives up a chance to singlehandedly change Hufflepuff's reputation forever, solely because it was the right thing to do. He would rather give up the glory altogether than take a victory he doesn't feel he earned—He and Harry both saved each other in the maze, they both earned the victory, and by god they're both going to share in it.
Up to Eleven when you realize that, in giving up unspeakable glory for Hufflepuff solely because he doesn't feel he's earned it fairly, Cedric is upholding everything that makes his House great. Loyalty. Fairness. Equality. Integrity. He genuinely believes that he and Harry have won this tournament by helping each other, that they have both shown strength and skill and courage to get here, and that the only fair and honest way to end it is to claim victory together, as equals. You have to be a lot of things to make a choice like that; useless and stupid are not among them.
Dumbledore's eulogy for Cedric. The Ministry is desperate to deny Voldemort's return; Dumbledore knows that sweeping that under the rug will also sweep Cedric's valor along with it, and there's no way Dumbledore will allow that.
A very small, subtle one in The Goblet of Fire. Harry has rescued Ron and Gabrielle from the Lake when "[...]Percy, who looked very white and somehow much younger than usual, came splashing out to meet them. [...] Percy seized Ron and was dragging him back to the bank ("Gerroff, Percy, I'm all right!")" Percy, who has always been seen as pompous and annoying, caring more about his job than his family, was plainly terrified for his little brother despite knowing Dumbledore would never have let anything happen to him.
While the entire scene where Dumbledore, Hermione, and Harry confront Hagrid after he is outed as Half-Giant by Rita Skeeter is this, the part where Dumbledore casually mentions that many parents have written letters in Hagrid's defense is touching. It's not just that his friends love him, it's that many people who have known him do so as well that just makes it that much more awesome.
The strength and hope that Harry and co take home with them at the end of the year (particularly in the film), even though the entire wizarding world is about to enter into utter turmoil.
If it hadn't been fake and self-serving, Moody comforting a distraught Neville after showing off the cruciatus curse in lessons, as Neville has just seen exactly what happened to his parents. Harry even notes that telling Neville what Profeessor Sprout thinks of his Herbology skills and lending him a book about the subject is the perfect way to cheer him up.
Harry giving his winnings to Fred and George after the Diggorys refuse, pointing out the world could use a few laughs with what's coming.
Ron is casually and unthinkingly kind to Dobby gifting him with a jumper and additional socks. He has little enough but is willing to share what he has.
Ron's indignation at Karkaroff's biased scoring with regards to Harry and Krum, and then also Harry realizing that most of Hogwarts now support him as much as Cedric.
Snape rolling up his sleeve to show Cornelius Fudge his Dark Mark, in hopes that Fudge will realize that this means that Voldemort is really back. Snape intentionally exposed his own past misdeeds in order to defend Dumbledore and Harry. It's also a strong indicator of where Snape's real loyalties are, since he could have just as easily passed for a servant of Dumbledore without making this gesture, while it would have been difficult to explain if any witness had reported it to Voldemort.
When Mr. Weasley scolds Fred and George for giving Dudley a Ton-Tongue Toffee that made his tongue turn purple and grow four feet long, their response is that they gave it to him for being a great bullying git ("isn't he, Harry?"). It becomes oddly sweet if you interpret the prank as the Weasleys getting revenge for Harry in a Big Brother Instinct-ly sort of way.
But of course they would- they went with Ron to get Harry early in Chamber of Secrets. They saw the worst of the treatment the Dursleys doled out to Harry and aren't about to forgive it.
Viktor's very honest, very sweet crush on Hermione. This is one of the most famous people aliveIn-Universe. A world-famous Quidditch player, with hundreds of admirers... and he wants the outspoken, nerdy girl who doesn't care one whit that he's famous. His feelings for her are strong enough that Hermione's the one taken into the lake as bait for Viktor, and later books confirm that they kept in touch and that he was Hermione's first kiss. (And in Deathly Hallows, it's implied he still has feelings for her, though he takes it well when he finds out she's now interested in Ron.) We don't see too much of their brief romance, but it's obvious Viktor really, really cared for her. Even most Romione fans can't bring themselves to hate the guy.
Furthermore, it's just as sweet for Hermione. This is a Bookworm whose close friends can be counted on the fingers of one hand, and who, it's implied, has low self-esteem. Now here's one of the most famous people in the Wizarding World, who could get dozens of "admirers" just by crooking a finger...and he chose her, asked her out, treats her like a beautiful woman (which neither Harry nor terminally-oblivious Ron have ever done), gives her a (probably fairly chaste) kiss, and still keeps in touch with her later. How sweet is that?
When Harry is about to enter the fireplace in the Dursleys living room to go to the Burrow he bids them goodbye, out of politeness more than anything else, and they typically ignore him. Mr Weasley stops Harry for a moment and essentially shames Uncle Vernon into returning the goodbye. It's nice to see someone stand up to the Dursleys treatment of Harry for once and it really highlights how the Weasleys are more family to Harry than his last remaining blood relatives who've raised him.
McGonagall's response after she, Snape and Dumbledore rescue Harry from Crouch Jr, which also doubles as a Tear Jerker. At first she's close to tears once Harry's out of danger, though she puts up a brave front in Mama Bear mode. She notices how shaken Harry is, that he's got an injured leg that hasn't been treated, and whispers to him to come to the hospital wing. When Dumbledore overrides her, she protests, "Dumbledore, he ought to- look at him- he's been through enough tonight-"
To cap it off, she calls out Fudge for bringing a Dementor in on school grounds, for bothering Harry while the latter is trying to sleep after his rough night, and for claiming that Crouch Jr. was a "raving lunatic" when two people — Cedric and Crouch Sr. — are dead because of him. She's a strict professor, but you do not mess with students in and out of her House.
From the Film:
Dumbledore talking to Harry after the end of the end of year feast ("Remember Cedric") about how he has friends at Hogwarts and isn't alone... then lightly brushes his cheek with his hand on his way out of the room. Dumbledore was rather out-of-character earlier in the film ("HARRYDIDYAPUTYANAMEINTHEGOBLETOFFIRE??") but that bit right there helped make up for it.
All the students are being taught to dance for the Yule Ball, and while the girls are all eager, none of the boys leave their seats. Then you see Neville hesitate (clearly trying to work up the nerve) before getting up to dance. Later, we see Harry and Ron entering the Gryffindor dormitory to find Neville, in his pajamas and dancing shoes, practicing the waltz by himself, humming a tune as he goes. Even later than that, after the party, Neville comes back later than everyone else, still humming and twirling round.
To some, the fact that Steven Kloves removed the part about him first asking Hermione and being taken by Ginny as a sympathy date makes the whole thing really sweet, as it implies that he was genuinely excited about going with Ginny and that even a nerd like him could get a date.
Fleur's reaction to Harry having saved her sister really serves to humanize her character; despite getting almost no lines in the film, Clemence Poesy did a wonderful job in that one small moment.
Fleur:(In tears) You saved her, even though she wasn't yours to save. My little sister. Thank you! (Kisses Harry on both cheeks and stands to face Ron.) And you. You helped! Ron: Well...yeah, a bit. (Fleur giggles and kisses Ron on both cheeks before walking away, leaving him stunned.) Ron:(Under his breath) Merci.
Hermione wrapping Harry with her towel and giving him a kiss on the head.
McGonagall gets three in one scene. She's less than a footfall behind Dumbledore as they burst in on Harry and Moody, she holds an arm out protectively when Harry passes her and she is the one to hold Barty Crouch Jr at wand's length when he lunges for Harry.
A small one, just before the first task when Hermione is talking to Harry between the tent doorway, trying to give him advice.
Hermione: The key is to concentrate. After that, you just have to- Harry: Battle a dragon. Beat. Hermione suddenly starts sobbing and comes through the doorway to hug him.
Basically, Hermione's whole relationship with Harry during the film. It really cements their whole Like Brother and Sister dynamic, the way she gives him advice and tries to comfort him during the tournament, and moments where, with anyone else, it would seem romantic, but with these two, it's just to show how much they care about each other.
Viktor telling Rita Skeeter to leave the tent when she bothers Harry and Hermione.
Viktor: "You have no business here. This tent is for champions, and friends."
It's especially nice because Hermione was in the tent, but Viktor knows she was only there to comfort Harry.
Unlike the book, in which he dances with Professor Sprout and Madame Maxime, neither of whom he interacts with much, Dumbledore and McGonagall share a dance here.
After the two of them are transported to the graveyard, Harry's scar begins bursting with pain and he collapses. Cedric immediately drops down to ask him what's wrong and, upon seeing a mysterious figure approaching, stands up and takes out his wand to defend himself and Harry. Too bad there was nothing he could do to block the Killing curse.
When all the spirits of people killed with Voldemort's wand emerge and attack him, Lily's is the first to reach him to give Harry time to escape; once again, Voldemort is beaten by a mother. Her words hurt quite a bit too, because she knows her son won't see her again.