"I see," said Aunt Marge. "Do they use the cane at St. Brutus's, boy?" she barked across the table.
Uncle Vernon nodded curtly behind Aunt Marge's back.
"Yes," said Harry. Then, feeling he might as well do the thing properly, he added, "all the time." (2.1.78-81)
Harry's dry sense of humor doesn't get to come out and play all the time, but we get a great demonstration of it here, as he manages to find the absurd in his overall crappy situation.
With a feeling of unease, Harry saw Stan's eyes move tot he scar on Harry's forehead.
"Woss that on you 'ead?" said Stan abruptly.
"Nothing," said Harry quickly, flattening his hair over his scar. If the Ministry of Magic was looking for him, he didn't want to make it too easy for them. (3.24-26)
Poor Harry – he's always trying to avoid attention. So it's no wonder that, when he can get away with it, he fibs to keep the focus away from himself.
"They'ad a job coverin' it up, din' they, Ern?" Stan said. "Ole street blown up an' all them Muggles dead. What was it they said 'ad 'appened, Ern?"
"Gas explosion," grunted Ernie. (3.76-77)
Details like this really emphasize how separated the wizarding community is from the wider Muggle world. Being a wizard is a lot like being a secret agent, and lying is often a necessary part of the job.
Unless Harry's eyes were deceiving him, Fudge was suddenly looking awkward.
"Circumstances change, Harry [...] We have to take into account [...] in the present climate [...] Surely you don't want to be expelled?" (3.137-138)
For a politician, Fudge is a pretty lousy liar. We can't decide whether to give him props for that or not. Stylistically, the pauses between Fudge's phrases, and his inability to complete a sentence, demonstrate his awkwardness.
"Harry's got a right to know. I've tried to tell Fudge, but he insists on treating Harry like a child. He's thirteen years old and –"
"Arthur, the truth would terrify him!" said Mrs. Weasley shrilly. (4.3.25-26)
Arthur Weasley really ties the theme of truth to themes of childhood here. Throughout this book, truth is associated with being an adult – you have to be old enough to hear certain things.
"You haven't got any of these subjects today. It's only Defense Against the Dark Arts this afternoon."
"Oh yes," said Hermione vaguely, but she packed all the books into her bag just the same.
"D'you get the feeling that Hermione's not telling us something?" Ron asked Harry. (7.1.82)
Cool character detail alert – Hermione never actually lies about her Time-Turner. She instead opts to change the subject, give a vague response, or just remain silent.
"Dumbledore told them that their best chance was the Fidelius Charm."
"An immensely complex spell," he said squeakily, "involving the magical concealment of a secret inside a single, living soul. The information is hidden inside the chosen person, or Secret-Keeper, and is henceforth impossible to find – unless, of course, the Secret-Keeper chooses to divulge it." (10.3.147-149)
Like so many of the spells in the Harry Potter books, the Fidelius Charm plays a thematic role. Fidelius is like the word "fidelity," which means loyalty or faith. This is fitting since the charm itself is about much more than just keeping a secret. It's really about loyalty and the decision to keep a secret. The Secret-Keeper can choose to divulge, but as long as that person chooses to stay silent, the secret remains safe.
Why had nobody ever told him? Dumbledore, Hagrid, Mr. Weasley, Cornelius Fudge [...] why hadn't anyone ever mentioned the fact that Harry's parents died because their best friend had betrayed them? (11.1.2)
Themes of betrayal and loyalty are really important in this book. Here, Harry himself feels betrayed by all the adults who committed a lie of omission.
Snape's sallow skin had gone the color of sour milk.
"And did the headmaster tell you the circumstances in which your father saved my life?" he whispered. "Or did he consider the details too unpleasant for precious Potter's delicate ears?" (14.3.78-79)
Once again, Harry's youth is an issue here, as it prevents him from hearing the whole truth about things. Contrast Snape's mean take on Harry's youth to Molly Weasley's protective streak towards "young" Harry earlier in the novel.
"You killed my parents," said Harry, his voice shaking slightly, but his wand hand quite steady.
Black stared up at him out of those sunken eyes.
I don't deny it," he said very quietly. "But if you knew the whole story."
"The whole story?" Harry repeated, a furious pounding in his ears. "You sold them to Voldemort. That's all I need to know." (17.104-107)
This idea of the "whole story" is really significant. As Harry learns in this book, there aren't just truths and lies, but mixtures of the two. The "whole story" about Sirius is a really complicated thing and, for the angry Harry, it's almost easier to just get the slightly simpler version. The details in this passage are worth noting too – the body language and tones of voice tell us a lot of Sirius's and Harry's respective states of mind here.
"NO!" Hermione screamed. "Harry, don't trust him, he's been helping Black get into the castle, he wants you dead too – he's a werewolf!"
There was a ringing silence. Everyone's eyes were now on Lupin, who looked remarkably calm, though rather pale.
"Not at all up to your usual standard, Hermione," he said. "Only one out of three, I'm afraid." (17.143-4)
Though Hermione was rocking her Jack McCoy impersonation during her Q&A sessions with Black and Lupin, she gets a bit over-the-top here. Truths in this novel often do double-duty as bombshells, and the revelation about Lupin being a werewolf is no exception. We love how Lupin maintains his calm and droll demeanor in spite of all the drama.
Lupin's face hardened, and there was self-disgust in his voice. "All this year, I have ben battling with myself, wondering whether I should tell Dumbledore that Sirius was an Animagus. But I didn't do it. Why? Because I was too cowardly. It would have meant admitting that I'd betrayed his trust while I was at school, admitting that I'd led others along with me [...] and Dumbledore's trust has meant everything to me." (18.52)
Lupin delivers a rocking mini-soliloquy here, in which he gives us great insight into his character, and into the difficulty of confessing a wrong to someone we trust and admire.
"But what about Sirius Black?" Hermione hissed. "He could be using one of the passages on that map to get into the castle! The teachers have got to know!"
"He can't be getting in through a passage," said Harry quickly. [...]
Harry hesitated. What if Black did know the passage was there? (10.3.85)
The detail of Harry's super quick response to Hermione's super logical objection to the super cool Map (we'll stop now) is really key here. Harry doesn't want Hermione to be right, so he quickly comes up with a whole series of reasons why she's wrong, even as he's hesitating and wondering if she is indeed right. Sometimes the most dangerous lies are the ones we tell ourselves, which is a lesson Harry has to learn in Book 3.