Chapter 20 - "Lord Voldemort's Request" - In which Ginny fights with Dean and Ron with Lavender, Luna delivers a message to Harry of a lesson with Dumbledore, and Harry arrives at the lesson to find Trelawney being asked to leave. Dumbledore makes Harry feel guilty for not procuring Slughorn's memory, but they view two new memories: in the first, Riddle visits Hepzibah Smith and sees Slytherin's locket days before her death; in the second, Riddle asks Dumbledore for the D.A.D.A. post at Hogwarts, which Dumbledore admits began the curse on the position.
Malfoy, McLaggen, and Lavender All Annoy Harry
[Lavender] corners [Harry] to ask him about [Ron], and [Harry] discovers that [Ron] has been faking sleep every time [Lavender] has visited him in the [hospital wing].
[Harry] drops by to visit [Ron] in the [hospital wing], where they discuss [Harry]'s annoyance with [McLaggen] and the status of Ron's desire to end his relationship with [Lavender].
On his way to the [Quidditch] match, [Harry] runs into [Malfoy] with [Crabbe] and [Goyle], [Polyjuiced] as two little girls, walking off into the castle.
Luna Comments on Quidditch
[Harry] arrives at the [locker room] just in time for the game, and [Ginny] questions him on where he's been.
[Gryffindor] faces [Hufflepuff] in [Quidditch]. [Luna Lovegood] commentates, the Gryffindors hammer [Zacharias Smith], and [Cormac McLaggen] makes a fool of himself and knocks [Harry] out with a [Bludger], leading to a [Gryffindor] loss.
[Harry] wakes up in the [hospital wing] with a cracked skull, and discusses the [Quidditch] match and [Malfoy] with [Ron], until [Ron] falls asleep and [Madam Pomfrey] goes off to bed.
Lying in the [hospital wing] during the night, [Harry] calls [Kreacher], who he soon discovers is in the middle of a fight with [Dobby] that [Peeves] is watching gleefully. Once he stops the fight, [Harry] sets the two [house-elves] off to tail [Draco Malfoy] and report back.
After he and [Ron] are released from the [hospital wing], [Harry] walks to breakfast with [Ron] and [Hermione], learns that [Ginny] and [Dean] have had a fight, unknowingly passes a [Polyjuiced] [Crabbe] or [Goyle] in the hallway, and gets a note from [Luna] announcing his next lesson with [Dumbledore].
[Lavender] and [Ron] have a fight, putting [Hermione] in a good enough mood to let [Harry] copy her homework.