Heartwarming: Harry Potter and the Half-Blood Prince
From the Book
"I am not worried, Harry. I am with you."
Luna says, "I enjoyed the [Dumbledore's Army] meetings too. It was like having friends." Later in the same scene, Harry tells a rude girl that all the people in his compartment are his friends. Luna says, "People expect you to have cooler friends than us." And Harry replies, "You are cool." Pretty much any scene where anyone is nice to the optimistic yet sadly abused Luna is heartwarming because she deserves to have kind friends. What makes it even better is that it's a Call Back to the previous book, when Harry had been resentful and humiliated by the mere sight of Cho seeing him sitting with people like Neville and Luna. It shows how much Harry had grown up since then.
Harry gets Dumbledore back in Harry Potter and the Half-Blood Prince. He notes how Rufus Scrimgeour accused Harry of being "Dumbledore's man through and through." Dumbledore notes, amused, how very rude that was of him. Harry then says he effectively accepted it as a compliment... and suddenly notices how very damp Dumbledore's eyes seem. What perhaps makes this moment even better is this exchange right at then end when Harry and Scrimgeour meet at Dumbledore's funeral:
Scrimgeour: I see you are— Harry: Dumbledore's man through and through. That's right.
The fact that throughout the book, Harry does not drop the fact that Stan Shunpike, of all people, has been convicted as a Death Eater and thrown in Azkaban. He only met him a few times, but Harry knows Stan (along with many others) is innocent. (It's also heartwarming to find that Dumbledore has been trying to get Stan set free too.)
In Half-Blood Prince, Harry asks Luna to accompany him to Slughorn's Christmas party, and Luna is thrilled. The scene is sad, funny, and heartwarming; it's very well done. And despite the various sideplots also being developed at the party, we still get to see Luna thoroughly enjoy herself.
Yes, that's right - Luna knows she is different, but doesn't care in the slightest and is perfectly happy being totally different to everyone else, because she has friends that care for her.
When Ron tells Harry about Unbreakable Vows, he mentions that Fred and George almost made him take one as a kid, but Mr. Weasley stopped it just in time. He notes that it was the only time he'd ever seen him as mad as his mother gets. Something about that small mention of the Papa Wolf moment really did it for this troper.
Throughout Half-Blood Prince, Molly Weasley, convinced that Fleur Delacour was a vain, shallow, and snobby girl, was dead-set against Fleur and Bill's wedding. At the end of the book, Bill is slashed by Fenrir Greyback, is horribly disfigured, and may have some werewolf-ish tendencies. Molly is devastated, upset that "he was going to be married." Fleur asks Molly what she meant by "was", and yells that she doesn't care if Bill looks different, all that it will prove is that her husband is brave. The scene ends with Molly offering Fleur her great-Aunt's tiara to wear in the wedding; Fleur thanks her coolly, and then the two collapse into a hug and cry hysterically.
Fleur:(to Mrs. Weasley) And what do you mean by zat? What do you mean "he was going to be married?"... You theenk Bill will not wish to marry me anymore? You theenk, because of these bites, he will not love me?... Because 'e will! It would take more zan a werewolf to stop Bill loving me!... You thought I would not weesh to marry him? Or per'aps, you hoped? What do I care how he looks? I am good-looking enough for both of us, I theenk! All these scars show is zat my husband is brave! And I shall do zat. (she takes the medicine and starts treating Bill)
The teachers all deciding, at the end of Half-Blood Prince, that Hogwarts must remain open.
The scene where, after Fleur says she loves Bill despite being scarred, Tonks shakes Lupin yelling at him that Fleur loves Bill no matter what, and she loves him even if he's a werewolf.
"It is high time your grandmother appreciated the grandson she has, rather than the one she thinks she ought to have." — Minerva McGonagall to Neville Longbottom. Professor, you rock.
In Half-Blood Prince, after Harry saves Ron from being poisoned and the Weasleys are huddled around his (Ron's) sickbed, Mrs. Weasley remembers every time Harry has saved one of them and we get this golden line from Mr. Weasley:
Mr. Weasley: It was a very lucky day for the Weasley family when Ron decided to sit in your compartment in The Hogwarts Express that day.
At the end of the book, Harry breaks up with Ginny because he knows that she'd be in constant danger otherwise. He intends to do essentially the same with Ron and Hermione, but:
Ron: We'll be with you, Harry. At your aunt and uncle's. And then we'll go with you. Hermione: You said to us once before that there was time to turn back if we wanted to. We've had time, haven't we? Ron: We're with you, whatever happens
Ron and Hermione making up after not speaking for a good chunk of the book, especially her freaking out after he is poisoned and him muttering her name in his sleep.
Ron's boasting about Hermione's skill at apparition, after their multi-chapter big fight earlier in the book, is very sweet in its own way.
Ron: "Oh, she was perfect, obviously!"
From the Film
Harry comforting Hermione after Ron and Lavender get together.
Ron and Hermione insisting that they will go with Harry on his Horcrux hunt, no matter what.
Everyone will always be split over things they change in the movies, but you'd have to be The Stoic to not feel a tug at the heartstrings in the sixth movie when, after Dumbledore dies and the Dark Mark is cast, Ginny is comforting a sobbing Harry and everyone, teachers and students, raise their wands and together vanquish the Dark Mark from their castle.
That scene is made even more heartwarming by the reactions of McGonagall, Hagrid and Madame Pomfrey. Dumbledore knew more about McGonagall's past than anyone else - she's just lost her best friend and looks utterly broken (she even gulps later to stop herself from crying); Hagrid is too sad to do anything and, when the wands (and Umbrella, in Hagrid's case) are raised, Madame Pomfrey is barely a second behind McGonagall and is crying unashamedly. Hurt their headmaster, and Hogwarts will unite.
Horace Slughorn talking about the fish that Lily Potter gave him; again, both a heartwarming moment and a tearjerker, and also remarkably startling since the lead-in lines to this speech had been part of a Crowning Moment of Funny.
Horace Slughorn: It was a student who gave me Francis. One day I came down to my office, and there was a bowl with only a few inches of clear water in it... and there was a flower petal floating on the water. Before my eyes it started to sink, and just before it hit the bottom, it transformed into a wee fish. It was a beautiful piece of magic, wondrous to behold. The flower petal was from a lily... the day Francis disappeared was the day your mother...
After Dumbledore dies, and the whole class puts their wands up in the air to get rid of the Dark Mark in the sky, we cut to the next morning. The scene alone with McGonagall and Harry was very sad yet heartwarming, but what had this troper burst to tears was when The Trio went up to the astronomy tower, and discussed what their next move would be now that Dumbledore is dead, and now that they know that the Horcruxes are the key to defeating Voldemort. Harry is determined to find them all by himself, but Hermione quite funnily retorts to him that he couldn't do it alone, with Ron agreeing. They then all huddle up on the balcony of the astronomy tower as they watch Fawkes the phoenix fly away, across the black lake and into the morning sun. Not really heartwarming in description, but good lord. The way they did it... with the cinematography... and then when placed into the context of the events that had just occurred.... and when you put on top of that that this is basically signaling the beginning of the end of the series, I began to cry. For people like me, who've grown up with the films more so than the books, who've grown up with the actors and their characters (and for whom the viewer can genuinely see the camaraderie that they have for each other)... it just... ahhhhh. It was a poetic and heartwarming moment on The Power of Friendship and the loss of innocence.
YMMV (shipping and all that) on the moment where Ron mutters "Hermione" in his sleep since Lavender was listening, but the part where Hermione holds his hand is sweet, especially in the wake of all that happened between them.