Alecto and Amycus are nothing but ugly cyphers in canon, so it's very interesting to see a story that uses them in a way that makes them more than cardboard cutout Death Eaters. Empathy for the two of them is something that is difficult to create, but you manage it quite handily.
And Pettigrew's motivations for betraying his Gryffindor friends are never really made clear, so the idea that someone could be genuinely interested in *him*, that someone would see him as clever and talented in his own right and not as merely the least of the Marauders, that someone would think him attractive and even sexy, must have been a heady brew indeed. You even humanized Greyback - a near impossible feat, I'd have thought - while letting us see that he is still not someone to like. Well, done, Mystery Author!