Can I just say that I love Fred and George here? Their uprising against evil, authoritative rule is inspiring – vive la resistance! It’s sort of neat too how we get multiple examples all at once of kids out-magic’ing grownups: Fred and George’s uprising, Hermione’s sneak pimples. (Is this the first time we’ve seen evidence of students out-magic’ing adults? I can’t remember.) And then everything/everybody from Dumbledore’s locked office to the Hogwarts teachers to Peeves conspire to support them. It really is a beautiful turning point in the series.

The James and Sirius bullying Snape scene is so gross. It reminds me so much of the Death Eaters levitating those muggles upside down in the air so that you could see their underwear at the Quidditch World Cup – and I’m sure that similarity was intentional by JKR.
My Harry Potter book club has speculated before about how a wizard from each house might “go dark” and this is probably what it looks like for a Gryffindor, letting power and glory go to their head. This is probably the best reminder we get that, although James and Sirius are “good guys,” they came from wealthy, old, pureblood families and may well have grown up as spoiled, entitled pricks.
Of course adolescence can be a dark, confusing time for any teenager and we do have evidence that later in their lives they matured into more thoughtful adults. Frankly, the character journey of them becoming thoughtful adults given this low starting point is a tale I would like to know. Regardless, it gives Sirius real gravitas when he tells Harry that the world isn’t split into good people and Death Eaters; he knows first hand what it’s like to move along that spectrum.
My heart really, really breaks for Harry through this, though. A boy who never knows his father has a tendency to idolize his memory and ugh, what a cold slap in the face that his romanticized version of his father might not quite be real. This entire series is about growing up and this right here is one of the biggest “innocence lost” moments of them all.