Literature: Harry Potter and the Half-Blood Prince
"Apparently I underestimated you, Potter. Who would have thought you knew such Dark Magic?"
— Severus Snape
Harry Potter and the Half-Blood Prince is the sixth and second-to-last Harry Potter book, published July 16, 2005.The Ministry has finally accepted that Voldemort is back, but that's not really making the situation any better. With everyone terrified, obviously unjustifiable arrests, and misinformation still being printed, just in the other way, and events play out to show that the Ministry can't really stop Voldemort in its current form.But while those events linger over the plot, the action stays fully grounded at Hogwarts. Harry learns more about Voldemort's Back Story, becomes increasingly suspicious of Snape's loyalty and discovers an old potions textbook annotated with powerful spells and useful notes from its previous owner who identifies himself only as "The Half-Blood Prince". Draco Malfoy is tasked with something by Voldemort himself; and wacky romantic hijinks ensue for everyone.As Word of God has noted, Half-Blood Prince is where the serialization of Harry Potter hit its max. Where all five of the previous novels ended the main plot, Half-Blood Prince's ending builds up to an emotional release but simply prepares the reader for Deathly Hallows to start up at a much faster pace. Also, due to the fact that Executive Meddling forced Rowling to slim down Chamber of Secrets, there is a a lot of Fridge Brilliance here when compared to Chamber.Followed by Harry's seventh year, in Harry Potter and the Deathly Hallows.
Tropes exclusive to this book or at least especially prominent:
Acquitted Too Late: Morfin Gaunt, who was framed by Voldemort for the murders of Tom Riddle Sr. and his parents. Dumbledore found evidence Voldemort was the real culprit but Morfin didn't live long enough to see the verdict being overturned.
Acting Unnatural: Hermione attempts to act casually in Bogin's & Burke's and immediately gets noticed.
Actor Allusion: Whether intentional or not, Slughorn called Ron 'Rupert', a reference to Rupert Grint, who plays Ron in the movies.
The Alcoholic: It's implied that the head of young Tom Riddle's orphanage, Mrs. Cole, is one. It's not surprising given the stress of running such an establishment - for over at least the last 11 years - and that Dumbledore's visit coincided with the threat of war with Nazi Germany.
Ambition Is Evil: Finally averted in the person of Horace Slughorn, which is nice given that he is a member of Slytherin, the Former Trope Namer. He has a tendency for favoritism, singling out people he hopes will benefit him in the future due to their talent or family connections, but even this is equal-opportunity and he doesn't hold (much) prejudice against other houses or non-purebloods. He is also genial, more likable than all prior Slytherins (Draco in Leather Pants notwithstanding), is ashamed of accidentally helping Tom Riddle's Start of Darkness, and isn't, you know, evil.
It's also mentioned that the people he singles out really do have knacks for going far in life (which is why he makes favorites of Hermione and Ginny, even though they aren't from prominent families). So it's really a win-win for both sides, with him providing opportunities to students that they might not get otherwise and them sending him various gifts in exchange. If you think about it, it's no worse then a College Professor giving a student they think has potential pointers and tips.
Played with. Tom Riddle Sr. had a reputation as being snobbish, but Merope effectively kidnapping and date-raping him with a Love Potion still comes off as morally wrong to many.
Also with Morfin Gaunt, Muggle-hater who was framed with the murders of Tom Riddle Sr. and his parents, all of whom were victims on their own right.
Draco, as the victim of Voldemort's manipulation and threats on his and his family's lives - he may not be a nice person (an understatement), but he is a 16 year old boy, and the book and movie both make clear that he is veering towards a nervous breakdown.
Beauty to Beast: Fleur to Bill. Also Voldemort's back story, due to his own efforts.
It's also because Voldemort believes this trope is in effect, so he will do everything in his power to kill Harry. Because of this, Harry will ultimately have no way to stop Voldemort other than killing him.
Beneath Suspicion: Nobody believes Harry as he argues that Draco is a Death Eater plotting against them, since Draco is mostly a joke to them by this point.
Big Man on Campus: Harry finds himself in this role now that he's Gryffindor Quidditch Captain and everyone knows he was telling the truth. The combination of celebrity, a growth spurt and everyone seeing the scars from Umbridge's detentions turns him into an unwilling Chick Magnet.
Bilingual Bonus: In Latin, fēlīx fēlīcis are both words meaning "lucky". note Those are the nominative and genitive forms of the adjective; essentially, they're two different ways of saying the same word whose use depends on the grammatical role played by the noun it modifies. Notably, Latin nouns and adjectives are often displayed this way in high-school textbooks.
As revealed by a memory given by Slughorn, one of the steps in creating a Horcrux is to commit murder.
Also, Dumbeldore has to cut his own hand to enter a cave Voldemort has protected with Dark Magic. His main reaction is disappointment at Voldemort's lack of imagination.
Breather Episode: Between the dark fifth and seventh books, most of this book is a pretty easy-going tale with a lot of exposition and teen angst (not to mention many jokes). That is, until the last few chapters.
In the fifth book, there is a joke when one of the Weasley twins tells that the lowest OWL grade is T (for Troll), and Harry wasn't sure if they were joking or not. In the beginning of the present book, the heroes receives their exam results and yes, Troll is an actual grade.
Call Back: And lots of them, some easy to miss. Why so many? Because this is Harry's last year at Hogwarts.
Such as Harry going to Diagon Alley with Hagrid and meeting Draco in Madam Malkin's... only Diagon Alley is no longer the wonderful wizard bazaar of the first book, but under war conditions.
The most notable call backs from this book go all the way back to Philosopher's Stone - EVERYTHING from Snape's first Potions class becomes relevant.
When Harry offers Ron a tainted drink, he says "Coffee? Tea? Pumpkin juice?" Exactly the same thing Umbridge had said to him the previous book when she was trying to get Harry to drink Veritaserum.
Calling Your Attacks: Mostly played straight, as in the previous books, but averted when Snape begins teaching non-verbal spells in Defense Against the Dark Arts.
Captain Obvious: Harry saying "Ghosts are transparent." (Why he said it made sense in context but still got him told "Ah, I see six years of magical education have not been wasted on you.")
The source of "You can't break an Unbreakable Vow." Harry snarks that he'd worked that much out for himself, and asks what happens if you DO break it. "You die."
The Chinese translation says that Slughorn is saying Ron's name wrong when we can all tell that from the dialogue.
Probably an attempt to prevent what happened following the initial english release which was some people wrote to J.K Rowling to tell her she got Ron's name wrong. *Facepalm*
Cassandra Truth: Harry, dear, when you accuse someone of something it helps to have actual evidence backing it up. Somewhat subverted by the events of the next book, which reveals that Dumbledore was fully aware of Draco and what he was trying to do, if not exactly how, but it suited his plans to let Draco come after him, to protect him from Voldemort's wrath.
The first is when Hermione uses a Confoundus charm on Cormac to make him miss his last block, ensuring Ron gets the position of Gryffyndor Quiddich Team keeper.
The second is when Harry puts Felix Felicis in Ron's drink, which is forbidden; however, it turns out he didn't actually put it in. Ron only thought it did, and it gave him the confidence boost he needed to win. While the plan worked, Ron mocks Hermione's earlier attempts to stop Harry from putting the potion in his drink and then makes out with Lavender, hurting her badly.
Curb-Stomp Battle: Harry vs. Snape is quite possibly the single most one-sided duel in the book besides Snape's earlier bouts with Lockheart.
The fact that Snape is using Legilimency to see what spells Harry is going to cast before he casts them just makes it even more pathetic.
Made worse still in that Snape kept telling Harry to clear his mind if he wanted any chance on beating him; i.e. attempting to teach him a lesson while kicking his ass.
Dangerous Forbidden Technique: The creation of a horcrux is so forbidden that there's virtually no information on how to do it besides "kill somebody". Hermione searches the immense Hogwarts library, and finds only a single mention of them, which gives no information other than that there's something out there with this name, and it's really bad.
Dark Is Not Evil / Dark Is Evil: The new Defense Against the Dark Arts teacher Severus Snape imparts his personality onto the classroom and adorns the walls with plenty of pictures showing the various horrid things that happen to anyone who runs afoul of the Dark Arts.
Deader than Dead: Inferi. They're like zombies and thus have to be burned; other forms of magic such as Sectumsempra won't work because they have no blood and feel no pain.
Dedication: Rowling said that this book and her youngest daughter, Mackenzie, "were racing each other into the world", so she issued this dedication:
To Mackenzie, My beautiful daughter, I dedicate Her ink-and-paper twin
Designated Love Interest: Ginny. Part of the hate for the pairing of Harry and Ginny is because of Die for Our Ship, while the other part is rooted specifically to this. After her questionably rushed hook-up with Harry, most of the development of the pairing took place off screen. In fact, there's a time skip following their hookup where Harry describes it at as some of the happiest moments in his life, but the readers never actually get to see it.
Despair Speech: Slughorn gives one of these when he agrees to give Harry his memory about the time he told Tom Riddle about Horcruxes.
Destination Defenestration: Attempted on Fudge by Margaret Thatcher. Fudge is apparently so flustered by the memory that he gets his third-person pronouns mixed-up.
Disappointed In You: When Harry disappoints Dumbledore by not making much of an effort to get a memory from Slughorn, he would have preferred him to yell; "this cold disappointment was worse than anything."
Disproportionate Retribution: Hermione's SNEAK jinx in the previous book takes on a whole new level of menace when, months after being jinxed, Marietta still has the scars. Word of God is they will never come off.
Deconstructed with Merope's rape of Voldemort's father, which is portrayed as a very bad thing not just in and of itself but because it meant Tom Riddle wasn't conceived out of love, making him evil. The reason it's played for laughs with Ron is that Harry kept anything untoward from happening. And it's possible the Double Standard exists in the HP universe, and Merope was put in deliberately, to highlight it. Moreover, Harry certainly doesn't consider love potions "sweet and innocent", no matter who uses them—in fact, he actually compares them to Dark Magic at one point. (As they can be used to make a person act against their usual being, Harry probably has a point.)
Drunken Song: When Hagrid and Horace get drunk at Aragog's funeral, they sing a song called "Odo the Hero".
Easily Forgiven: Averted with Harry's relationship with the Ministry of Magic . While Rufus Scrimgeour (sort of) tries to patch things up, Fudge's smear campaign — combined with the new Minister continuing policies favored by Fudge and Barty Crouch — leave the schism between Harry and Ministry wide open for the remainder of the series.
Played straight and subverted when Snape notes that while Voldemort was not happy that his Death Eaters had abandoned him (and as we saw in Book 4, was intent on exacting over a decade of penance from them), circumstances forced him to be pragmatic. If he hadn't forgiven those who lost faith, Voldemort would have been left with only a handful of Lieutenants to support him in the Second Wizarding War.
Enfante Terrible: Tom "I can do bad things to people who annoy me. I can make them hurt if I want to" Riddle.
Et Tu, Brute?: Snape's murder of Dumbledore plays with it, although it is ultimately subverted in the next book.
Even Evil Has Standards: Even most dark spellbooks are reluctant to elaborate on the nature or creation of Horcruxes.
Evil Is Cool: Used In-Universe with Snape as the Dark Arts teacher. Harry, upon hearing him talk about the Dark Arts thinks, "It was surely one thing to respect the Dark Arts as a dangerous enemy, another to speak of them, as Snape was doing, with a loving caress in his voice?"
Evil Is Petty: Voldemort put a curse on the Defense Against the Dark Arts position because Dumbledore wouldn't give him the job when he attempted to reapply. In this instance, it's not too surprising considering it prevented Voldemort from acquiring relics of the founders he could use as potential Horcruxes.
There's an interesting, alternate interpretation of this as outlined in Fridge Brilliance. What comes across as pettiness is actually a brilliant piece of strategic warfare. Without a consistent DADA teaching curriculum, the up-and-coming generation of young Wizards would have been ill-equipped to fight the First Wizarding War.
Fake Memories: Horace has covered up his own memories of giving the young Voldemort information about the Horcruxes.
Fantastic Racism: Tom Riddle murdered a woman for her artifacts and framed her House Elf for it. Dumbledore tells Harry that the Ministry should have investigated further but didn't "...because she was a House Elf". Harry had never sympathized with Hermione's campagin as much as he did at that moment.
Foreshadowing: Hagrid mentions overhearing Dumbledore and Snape getting into an argument regarding a task Dumbledore entrusted Snape with. The next book reveals that the "task" was in fact Snape's "betrayal" and murder of Dumbledore, although it's more complex, being more comparable to Assisted Suicide as Dumbledore was dying anyways from the curse on Marvolo's ring.
When Harry catches a whiff of a love potion (which smells different to everyone "according to what attracts us"), he notes that it is a bit familiar, and he has smelled it around the Burrow. Shortly afterward, he notices that it's Ginny's perfume. Later on, he begins to develop serious feelings for her.
During the argument in Spinner's End, Bellatrix claims that Volddemort, at some point, entrusted her with his most precious something. It won't be clear until the next book that she's talking about the Hufflepuff Cup-turned-Horcrux in the Lestrange's Gringotts vault..
In the Christmas chapter: "She [Mrs Weasley] gave Lupin an annoyed look, as though it was all his fault she was getting Fleur for a daughter-in-law instead of Tonks."
Free Sample Plot Coupon: After Dumbledore tells Harry about the importance of destroying Horcruxes, the latter is concerned about the potential difficulty of finding said artifacts in the first place, but then the headmaster tells him that he had already destroyed Marvolo's Ring, and that Harry himself had destroyed Riddle's Diary in Chamber of Secrets, so there are only four more Horcruxes to worry about.
Getting Crap Past the Radar: When Ron and Hermione try and fix the former's misspelled essay due to a worn out auto-correct quill, one of the things Hermione notes is "Augury doesn't begin with O-R-G' either.'
A Glass in the Hand: Dean Thomas after seeing Harry and Ginny kiss. Romilda Vane seems to be even angrier, as she is described as looking like she's about to throw something.
"Meanwhile, the Hogwarts library had failed Hermione for the first time in living memory. She was so shocked, she even forgot that she was annoyed at Harry for his trick with the bezoar."
The Greatest Story Never Told: We are never told who in the Wizarding World started spreading around that Harry was any sort of "Chosen One", or why the general public may feel that there was one to be "chosen" in the first place.
He Who Fights Monsters: Harry does a stupid, stupid thing and tries out a spell on another human being despite the only thing he knew about the spell was that it was marked "For enemies". Harry learns a lesson in responsible spellcasting and how dangerous casting unknown spells can be. He pays for this in the book, and is darn lucky a person was nearby who could set it right. (In the movie, he doesn't have any comeuppance.)
Hope Spot: Arguably Scrimgeour succeeding Fudge as Minister of Magic. As the former Head of the Auror Office, he's a veteran of fighting Dark Wizards and seems the perfect choice for a wartime leader. Then he continues or resurrects policies of Fudge and Barty Crouch Sr. It ends up making things worse.
I Need to Go Iron My Dog: Dumbledore uses this method to leave Harry alone with Professor Slughorn so as to persuade him to return to Hogwarts — specifically, by asking to use the loo. The fact he returns afterwards with a magazine he wants to keep "for the knitting patterns" just highlights his eccentricity and hilarious kookiness. It was still a nice bit of obfuscation.
Insecure Love Interest: This is Lupin's reason for not getting together with Tonks. He comes round in the end.
Insult Backfire: "Dumbledore's man through and through, aren't you?" "Yeah, thanks for clearing that, Minister."
Inverted Trope: In the previous book, Harry was wrong and everyone else was right That Voldemort was trying to lure Harry into the Department of Mysteries - Harry's being mislead resulted in the death of Sirius. This is switched around in this book, as Harry is right and everyone else is wrong, and again resulting in the death of a major character.
Irony: Snape stops teaching Potions class and teaches Defence Against the Dark Arts at Hogwarts and is replaced by Professor Slughorn. Previously Potions was Harry's worst subject because he hated Snape and never made the effort in class. In his first class with Slughorn he finds a second-hand book labelled as "the property of the Half-Blood Prince". Inside the book are vast amounts of hints that help Harry in his Potions classes, making it his best subject. Then the big reveal is that Snape is the Half Blood Prince. At one point in the book Harry even makes a throwaway remark that The Prince was a much better teacher than Snape. Dramatic irony at its finest.
Kick the Dog: Greyback attacked the five-year-old son of Ms. Montgomery when she refused to cooperate with the Death Eaters. The boy later died from his injuries.
Kick the Son of a Bitch: After everything he did in Book 5 and the end of Book 4, it's hard to feel sorry for Fudge after he's forced to resign in disgrace.
Kill It with Fire: Dumbledore specifically states that fire is the most effective against Inferi. The Ring of Fire he uses in the cave is even in the British cover pictured above.
Kissing Discretion Shot: A literary version as Rowling brushes off their new relationship from the reader. We've sat through Harry's journey to find love, and Ginny's quiet pining after Harry for years - now that they are together, it's pretty much none of our business what they are doing in the quiet corners of Hogwarts.
Last Minute Hookup: Not only do Harry and Ginny become a couple close to the end after Harry spends a good portion of the book crushing on her, but they actually manage to break up before the end of the book! Doubly so because the novel glosses over the few weeks Harry grows closer to Ginny, in the span of a chapter going from crush to couple. The film rectifies this a bit by expanding Ginny's screen time and giving her more scenes alone with Harry.
Loophole Abuse: Defied when Harry orders Kreacher to spy on Draco. Mindful of what happened in Book 5, Harry makes sure to close every potential loophole that would allow Kreacher to tip off Draco.
Magic Feather: Harry pretends to give Ron a luck potion to give him confidence. A slight subversion in that the potion would have actually worked if added for real, but its use in contests is of course banned.
Horace is set up as the new-DADA-teacher of the book. Harry is as surprised as the reader to learn he's actually replacing Snape, who's moved positions after wanting the job for years.
Two previous Red Herring characters are behind the main plot, and this time Harry is on to them from the beginning. So is Dumbledore, but he's keeping quiet about it in case Voldemort catches on through Legilimency.
Militaries Are Useless: The aurors may qualify, depending on whether you consider them as an army or not. In the sixth book, they fail to kill or capture any Death Eater, put innocents in jail (where they are captured and Brainwashed by said Death Eaters) instead, and do nothing to prevent the ministry from being infiltrated by Voldemort.
Mind Rape: Dumbledore goes through this while drinking the potion guarding the locket Horcrux.
Never My Fault: During the meeting at Spinner's End, Snape sarcastically inquires if Bellatrix is still considered a confidant of the Dark Lord after the fiasco in the Department of Mysteries. Bellatrix responds that it was all Lucius' fault. However, it was her getting trigger happy which derailed the entire operation, got all the operatives except herself thrown into Azkaban, and exposed Voldemort's return to the Wizarding world at large.
Even better, Narcissa gets pissed that she's trying to shift the blame to her husband and calls her sister out on it.
Nice Job Breaking It, Hero: The 1940s-era Dumbledore choosing not to tell the other Hogwarts teachers about the young Tom Riddle's love of cruelty and bullying. If he had not given Riddle a chance to turn over a new leaf, Wizarding history would probably have taken a different turn.
No Celebrities Were Harmed: The unnamed prime minister that Fudge terrifies in the first chapter. If you go by the internal chronology of the books, it should be John Major, although the caricature reads more like a spoof on Tony Blair. But if it was Major, it would provide attentive readers with the amusing image of Margaret Thatcher throwing Cornelius Fudge out of her office window (although the idea of gray and unflappable John Major getting worked up to the point of attempting homicide is equally funny).
No Challenge Equals No Satisfaction: Voldemort's mother at first used a Love Potion to make Riddle Sr. fall in love with her. Then she decided that it didn't feel real because it wasn't genuine, so she neutralized the potion, hoping that he'd really be in love with her after it wore off. Unfortunately for her, he dumped her like a hot potato, abandoning her and her child.
Dumbledore's body-bind spell. There are hints throughout the books that this is a common and expected phenomenon — magic dies along with the wizard that performed it.
Not a Date: Harry and Luna at Slughorn's party. He makes it clear that they're going as friends, which she is perfectly happy with. Peeves, of course, overhears them and zooms off cackling about how "Potty loves Loony."
Not-So-Harmless Villain: Draco Malfoy. In the previous books, he was a bully, but not even a pawn when it came to Harry vs. Voldemort. But in this one, Harry will get serious trouble because of him.
Not Using the Z Word: Inferi are basically magical zombies with a different name. (The original voodoo/vaudou kind, not the modern post-George Romero kind.)
Obviously Evil: Tom Riddle, as a child in the orphanage, to the point where even though nobody can prove anything he scares everyone, even those who run the orphanage. By the time he gets to Hogwarts he becomes very good at hiding this, enabling him to fool everyone except Dumbledore, who met him before he adopted the act.
One Last Field Trip: Invoked after Dumbledore's funeral. Harry has lost his mentor and broken up with his girlfriend. He is going to drop out of school to hunt down Voldemort's Horcruxes. He is glad that he has "one last golden afternoon" to spend with Ron and Hermione.
Only Smart People May Pass: The protection around the Horcrux ensures that it's impossible for anyone (including Voldemort himself) to get at it without hideously torturing them.
Well, anyone who didn't think to bring along a second person (or elf) with them. Dumbledore sacrificed himself but could've made Harry drink the potion. R.A.B. had Kreacher. It's reasonably easy to imagine that Voldemort would likely just imperius a muggle.
Rasputinian Death: Dumbledore. Let's see.... He gets an arm nearly burned off from a curse — a curse that proceeds to slowly drain his life force away. Later he has to slice open his arm for a blood tribute. He drinks all that poison to retrieve the fake Horcrux. Then he gets a Killing Curse right in his chest and tumbles off the balcony of the tallest tower in Hogwarts.
Reality Ensues: At the end of Book 4, Fudge was informed of the return of the most dangerous terrorist in Wizarding Britain. The Minster of Magic responded by not only covering it up, but also wasting valuable time and resources persecuting and harassing the very people who tried to warn him. When Voldemort’s return is confirmed beyond any doubt, it ignites a scandal of epic proportions. Quite understandably, Fudge loses all public and political support and is forced to resign in disgrace.
Played with, as it's not delivered by the Big Bad, but Snape does give Harry a rather good one when they are dueling at the end — and, in hindsight, it's very easy to interpret as Snape getting one last chance to say to Harry, "No, seriously, get better at the things I was trying to teach you or you are going to frigging die."
Harry also delivers one to Rufus Scrimgeour.
Dumbledore also gives a small one to the Dursleys in the beginning of the book, calling them out on not bothering to treat Harry like a second son and instead treating him like a piece of trash, though he does remark that Harry turned out better than he could have under more loving circumstances, because Dumbledore was able to see what happened to Dudley, who had been given everything he'd wanted.
Rescued from the Scrappy Heap: In-universe example. Fleur's insistence on marrying Bill forces Molly to admit that her future daughter-in-law is a far, far better person than she had given her credit for.
The Reveal: Snape was the Death Eater who told Voldemort about the prophecy, bumping Lily and James to the top of his list. Harry, naturally, learns this minutes before going after a Horcrux with Dumbledore. It takes everything he has not to start tearing the office apart like at the end of the last book.
Separated by a Common Language: When Hermione says Harry has never been more fanciable, American readers may see that as Hermione simply calling Harry likeable, but British/Commonwealth readers will know that Ron is acting so jealous because Hermione has just called Harry desirable in public.
Sequel Hook: Harry's decision at the end to not come back to Hogwarts in favor of focusing solely on destroying Voldemort signals a radical departure for the final installment.
Shaggy Dog Story: Did you hear the one about how the Horcrux Harry and Dumbledore nearly killed themselves trying to retrieve from the cave turned out to be a fake, planted by someone else to buy the resistance some time for when Voldemort came back to get it?
Shipping Torpedo: A handful are especially prominent in this book, though play out in others as well:
Ron is not a fan of anyone dating his sister Ginny.
In flashbacks, Snape towards Lily and James.
In a more humorous example, this is initially Mrs. Weasley's reaction to Bill and Fleur.
Shout-Out: The captain of the Slytherin (the house known for cunning, ambition and lust for power) Quidditch team is named Urquhart.
Hagrid and Slugorn's drunken song, "Odo the Hero", may be a reference to Star Trek: Deep Space Nine.
Shown Their Work: When it is revealed that the only side effect Fenrir's bite will have on Bill is a preference for very rare steaks, Fleur declares that it is lucky that he is marrying her because "ze British overcook their meat." There is a French term "bleu" which is decidedly rarer than the British/American "rare". Essentially, it is just seared. The surface is cooked, but the inside is not really cooked at all.
Ship Sinking: Though not officially torpedoed until Book 7, this book effectively sank the ship of Harry×Luna. However, it does still give the readers some...
Ship Tease: Harry and Luna get some moments, such as him telling her she's cool, refuting his thoughts about her from Book 5 and when he takes her to Slughorn's Christmas Ball. After he asks her to go with him, Peeves also becomes a Ship Tease and starts singing, "Potty loves Loony!"
Shotgun Wedding: Merope was hoping to have one of these with Tom Riddle Sr., or at least have him stay with her due to her pregnancy.
Sickeningly Sweethearts: Bill and Fleur (as far as Ron and Ginny are concerned), Ron and Lavender (mainly the latter).
Some of My Best Friends Are X: Variant — the one bringing this up isn't the one being accused of prejudice. When Slughorn talks about how surprised he was that Muggle-born Lily was so good at potions, Harry mentions that one of his best friends is Muggle-born and she's the best in their year. Slughorn plays it dead straight immediately after, denying any insinuations that he's prejudiced by rapidly pointing out that he's got several favourite Muggle-born students.
Tampering with Food and Drink: Ron accidentally eats love-potion-spiked chocolates meant for Harry. Harry gets Slughorn to give him an antidote before things get out of control... and then he drinks poisoned wine meant for Dumbledore.
After Bill is mauled by Fenrir Greyback the Werewolf, Fleur still loves him. This is what finally convinces Ginny and Molly Weasley to accept her.
Inverted with Merope Gaunt and Tom Riddle.
Played straight with Lupin & Tonks. Though we're sure some fangirls will insist otherwise. After all, Lupin is actually handsome, its just his age and his lycanthrophy puts the odds against him.
Also played straight with Mr. and Mrs. Delacour.
The Unchosen One: Dumbledore makes a point of making Harry realize that, regardless of the prophecy, what Harry does is his own decision and no one else's.
Harry: But, sir, it all comes to the same thing, doesn't it? I've got to try and kill him, or — Dumbledore: Got to? Of course you've got to! But not because of the prophecy! Because you, yourself, will never rest until you've tried! We both know it! Imagine, please, just for a moment, that you had never heard the prophecy! How would you feel about Voldemort now? Think! Harry: I'd want him finished. And I'd want to do it.
Unusual Euphemism: "Chest monster" is certainly an original term, though anyone who's been an adolescent male probably has no trouble sympathizing.
Unwitting Instigator of Doom: Morfin Gaunt hexing Tom Riddle Sr. This simple act sets off a chain of events that not only ends up destroying both of their families, but also gives rise to the most dangerous Dark Wizard of all time.
What Do You Mean It's Not Heinous?: The Weasley twins essentially smuggling Love Potions into Hogwarts so that the female population of Hogwarts can use date-rape drugs on the poor, unsuspecting boys.
What Kind of Lame Power Is Heart, Anyway?: "So, when the Prophecy says, that I'll have 'Powers the Dark Lord knows not' it just means Love?" asked Harry, feeling a little let down. "Yes, just love" said Dumbledore.
Heart Is an Awesome Power: Love is precisely what saved Harry as a baby: Lily's sacrificial love is the source of his protection against Voldemort. It comes up again in Deathly Hallows, when Harry's self-sacrifice protects everyone.
What the Hell, Hero?: Harry calls out Scrimgeour on resurrecting Barty Crouch's policy of imprisoning suspected Death Eaters with no trial.
Harry using an unfamiliar spell, the effects of which were unknown, on Draco, resulting in Draco being severely injured. Fortunately Snape was able to heal him, being that he invented the spell, but Harry feels appropriately guilty for the incident. Somewhat justified in that Draco attempted to hurt him first. Regardless, the fact that Harry could well have killed Draco makes it a pretty morally questionable move.
Possibly justified in that Malfoy had been about to use the Cruciatus Cruse on Harry, even though this makes no sense, as that would have earned Malfoy a one-way ticket to Azkaban.
Xanatos Gambit: Voldemort's plan (ordering Draco to kill Dumbledore). The plan is to give Draco an impossible, likely-suicide mission in order to punish Draco's father, Lucius, for his failures. But, hey, if Draco succeeds, all the better.
Speaking of Voldemort, his job interview with Dumbledore during one of the flashbacks. If the Headmaster hires him, then it gives him access to potential Hogwarts relics for Horcruxes, a recruiting ground for young Death Eaters, and stores of ancient magic to tap. If Dumbledore doesn’t give him the job, that’s okay too since he’s using the brief access to the castle to hide one of his Horcruxes in the Room of Requirement.