Examples of HP as ring composition

Pensieve_Seeker COS- We are introduced to Aragog. HBP- We say good-bye to Aragog.

Flickerflame Some PS/epilogue ones: In PS we see Harry off to Hogwarts for the first time, the epilogue shows one of his sons going to Hogwarts for the first time. In PS we see Ginny impatient to go to Hogwarts though she's too young. In the epilogue her daughter is the same.

Pensieve_Seeker That's the first time I've ever heard anyone use those examples. Thanks for pointing them out. :)

Flickerflame Also there's introducing Draco and then Scorpius, but I'm not sure if that one is too vague.

Pensieve_Seeker It does seem rather vague. Book 1: Dumbledore is described as having what looks to be a broken nose. Book 7: We find out that Dumbledore not only has a broken nose, but also why it was broken.

LowriLorenza89 Harry buys Hedwig in Philosopher's Stone and she dies in Deathly Hallows. Harry is left at the Dursleys' house in Philosopher's Stone and leaves there for the last time in Deathly Hallows. Sirius is truly introduced in Prisoner of Azkaban (discounting mention of his name in Philosopher's Stone) and he dies in Order of the Phoenix. You could make an article listing 100 examples of ring composition in the series.