Have you ever read Dudley's Memories by paganaidd? Because it (and it's sequels) are my absolute favorite as far as actually acknowledging all the trauma left over from the Rowling's narrative. It's basically a "Dudley has a child who's got magic" story, except it almost immediately veers off into exploring how their childhoods damaged the both of them, and that's really the focus of it, is dealing with and moving on from the past in a healthy way.