First off, the stuff you do with pov leaves my brain in contortions. Having Dawlish as a pov character was genius, and you flesh him out as a three-dimmensional character, fully aware of his flaws, with a dry sense of humor and crap self-esteem. And that's awesome enough, giving us such a rare character, and making me believe completely and utterly that this is what happened to "cannon" Dawlish. But his pov is so over the top, so fanatically loyal, that it lets us see his greatest character flaw (loyalty, and no one would have ever thought they'd hear me call that a flaw) while seeing the two men he loves, both as flawed people (their flaws become extremely apparent to us because his viewing of them as perfect, as on a totally different plane from him, forces us to analyze everything they say and do far more carefully than we would otherwise) but also as wonderful, brilliant, radiant people, which is how we see the people we love. His adoration of them brings their flaws in to stark relief for the reader, because we know no one can be this perfect, and we're really searching for the imperfections, and we pity him so much because people you put on a pedestal like that inevitably let you down.
And the characters, the brilliant, moral, bloody-minded, flawed characters. First off, you included Bagnold! and drew her as a three dimmensional character in like three paragraphs! And Barty, oh dear Gods, I was crying so hard for Barty when he's standing on the streetcorner after imprisoning his son, all his confidence and certainty gone, saying his wife's name over and over and over. Yes, this is grief, more for the son he wanted and his wife than for actually imprisoning his son, but the scene showed what a toll this took on him; he's not an inhuman monster, but a man doing what he believes is right.
And I love the time shift, leaving out Mr. Crouch's demotion/shunting aside, and skipping directly to the Dementor's kiss of Crouch junior. I adored the fact that Dawlish's loyalty and love persisted through everything, and ached for him, because it could never be reciprocated.
And the fact that he essentially took justice in to his own hands with letting the Dementor kiss him, and how that ties back to the earlier conversation with Crouch senior about the Aurors being allowed to keep their special powers.. how the rather awful side of himself expressed in that conversation comes to fruition in the Dementor's kiss *loves like mad* The moral quandery implicit in that earlier conversation and then Dawlish's actions here is phenomenal; yes, there are some people like Crouch who can hold themselves back, have the ability to play God for a little while and then give it up for the greater good, but most of us can't. Bagnold was absolutely right about that. The idea of being able to rid the world of evil by giving up a few scruples is just too much for most people.
(My comment got so long here IJ is making me post the next bit separately)