What a lovely review! Thank you so much for being so specific about what you enjoyed. Although I try to be plotty sometimes, for me, writing Snarry is almost always a major dive into characterization. Giving them a past, a present and a future, a different way each time, is the challenge for me.
I did want to weave Severus' recording into the major theme of the story, that of having an epiphany and deciding which way one's life should turn. And I'm not sure most readers 'got' it, but you did--the fact that Severus had quite a few blind spots himself, when it came to his and Harry's relationship.
You're not the first reader to voice that they weren't too sure they wanted Julian in on Harry and Severus' new life. But I hold to the premise that any well-adjusted couple needs friends and family for two reasons: first, so they can keep their senses of self, and secondly, so they have the opportunity to experience each other through the eyes of others. Otherwise, I think the relationship can become too myopic.
It's always fun for me to find new and different occupations for these two. When I thought of the audiobooks, I almost peed my pants--it was so perfect, and Harry working with his hands, well, it seemed like something he'd enjoy, given his antipathy in general for the wizarding world at that time. Having Julian share that skill only seemed right.
I'm so glad you enjoyed it so much; I liked the new genres in these Games too, but most of the time I stick with what feels natural for me, and this was it. :)