Mrs Figg: I love her. Mostly because of the haHA-feeling I had when it turned out she was relevant. I had written her off as an early, pointless introduction, a mere illustration of Harry's horrible life. And here she is, relevant. Lovely. I like how her cats are relevant as well. In fact, I must say I am full of admiration for squibs. Certainly people like Mrs Figg and Mr Filch, who are involved with magic without being able to partake of it.

Dursleys: I like how they are used to make the point that normal teenagers don't listen to the news.

Dudley: his reaction to the dementors is one of the great puzzles of the books. I would love to hear it if someone has a theory. What are the things he hears inside his head? Voices from a memory?

Vernon: I can understand him. Once again, what happens when magic intrudes on his life is that someone in his family gets hurt. It is a fixed pattern. No wonder he is planning to throw Harry out.

Petunia: I just realised. Petunia says her information about dementors and Azkaban comes from "that awful boy telling her about them years ago". But that would have been Snape, the awful boy, wouldn't it. Not Potter?

Petunia herself is at her most interesting in this book, in this scene with all the letters. A history is hinted at, and it makes her more than a caricature. Her connection to the magical world hidden under the veneer of normalcy. I like it.

I take it the howler was from Dumbledore. Is that ever confirmed? I cannot remember.

Harry: his isolation is now a major theme, explicit and in the forefront. I like how it was present in earlier books as well. His reaction to it is understandable, but annoying. I also dislike Harry's tendency to think that the things they tell him not to do are punishments rather than precautions. It is annoying.

It is also interesting that Harry's treatment of Dudley (pre-dementors) is a reflection of Dudley's (and his parents') treatment of him before Harry was revealed as magical. He taunts, and Dudley is forced to take it, to force himself to not retaliate because he is now the weaker part. It is understandable. Definitely. But it is not a nice side to Harry. And when Dudley retaliates with information, words (which have traditionally been Harry's outlet), Harry reacts with threats of using his power.

Also, I notice that Harry's reaction to Dementors has changed. It is no longer his mother's scream, but the scene in the graveyard which comes to the fore.

Lupin: LupinLupinLupinLupinLupin!

Tonks: I could manage without her. Everyone knows Lupin and Sirius belong together. Tonks just gets in the way.

The rest of the Advance Guard are not so much introduced as ... suggested.