“’Moony, Wormtail, Padfoot, and Prongs,’ sighed George, patting the heading of the map. ‘We owe them so much.’"
-- Fred and George Weasley
Harry spends the weekend in hospital, Lupin returns to class and tells Harry about dementors, and Fred and George give Harry the Marauder’s Map. Harry uses a secret passage to join Ron and Hermione in Hogsmeade, they overhear a teachers’ conversation, and learn that Black is believed to have betrayed Harry’s parents and is his godfather.
Calendar and Dates
The action of the chapter begins the day after Gryffindor-Hufflepuff and continues through the afternoon of the day of the second Hogsmeade visit.
Interesting facts and notes
This chapter introduces the Marauder's Map.
The most memorable events of this chapter are the twins' early Christmas gift to Harry - the map itself - and the teachers' conversation in the Three Broomsticks about Sirius Black and his supposed involvement in the murder of Harry's parents.
It was a relief to return to the noise and bustle of the main school on Monday...
This the first Monday after the Gryffindor-Hufflepuff match.
Think about that for a moment. Malfoy's been wearing bandages since the first day of term - 1 September - and has been wearing them all the way into November, even though his arm was almost certainly undamaged after his initial visit to Madam Pomfrey.
...and celebrated having the full use of both arms again by doing spirited imitations of Harry falling off his broom.
Recollect that if it weren't for Dumbledore's timely levitation spell, Harry would've been killed by that fall.
Malfoy spent much of their next Potions class doing dementor imitations across the dungeon...
This is clearly on the same day as Lupin's return to DADA. Note that Potions is held before lunch on this day.
Snape is clearly ignoring all this arm-waving and flouncing around by Malfoy. It's a wonder that he manages to control a class with Slytherins in it if he ignores this kind of behaviour.
...Ron finally cracked and flung a large, slippery crocodile heart at Malfoy...
This tells us that crocodile hearts are a potions ingredient.
...which hit him in the face and caused Snape to take fifty points from Gryffindor.
Compare this to a Potions lesson about a year prior to this incident, in which Malfoy was flicking puffer-fish eyes at the Gryffindors and went unpunished (CS11). Granted, a crocodile heart is a much larger object and harder to miss, especially when it hits a student in the face...
Both Ron and Hermione had decided to remain at Hogwarts, and although Ron said it was because he couldn't stand two weeks with Percy...
This tells us that at Hogwarts, the Christmas holidays last for two weeks.
There were shelves upon shelves of the most succulent-looking sweets imaginable. Creamy chunks of nougat, shimmering pink squares of coconut ice, fat, honey-colored toffees; hundreds of different kinds of chocolate in neat rows; there was a large barrel of Every Flavor Beans, and another of Fizzing Whizbees...
With all of these sweets at Hogsmeade, it's no wonder it's always crowded.
...the levitating sherbet balls that Ron had mentioned...
...along yet another wall were "Special Effects" -- sweets: Droobles Best Blowing Gum (which filled a room with bluebell-colored bubbles that refused to pop for days), the strange, splintery Toothflossing Stringmints, tiny black Pepper Imps ("breathe fire for your friends!"), Ice Mice ("hear your teeth chatter and squeak!"), peppermint creams shaped like toads ("hop realistically in the stomach!"), fragile sugar-spun quills, and exploding bonbons.
"How about these?" said Ron, shoving a jar of Cockroach Clusters under Hermione's nose.
...examining a tray of blood-flavoured lollipops. Harry sneaked up behind them. "Ugh, no, Harry won't want one of those, they're for vampires, I expect," Hermione was saying.
Exceptional character moments
Draco Malfoy, wearing bandages on an uninjured arm for over two months just to get Hagrid into trouble.
Harry, who feels that in losing his Nimbus 2000 he's lost one of his best friends.
Lupin's controlled lack of reaction upon finding out that Snape had assigned an essay on werewolves to his third-year students, when the material was being brought up months too early.
Snape, who ignores Malfoy waving his arms around doing falling-off-a-broom and Dementor imitations throughout a Potions lesson.
The Weasley twins, who give Harry their most valuable aid to magical mischief-makers to cheer him up and get him into Hogsmeade, even though they could've just shown him the entrance to the secret passage without ever telling him about the map at all.
Ron and Hermione, opting to spend the Christmas holidays at Hogwarts, even though this is the third year running that Ron has done so and the second year running for Hermione.