Oh, Dudley. I very much like the background you gave him and that, despite the fact that he's only working in a pub and is not a high-powered high flier in the drill industry, like his dad, is still a virgin at 26 and has his mummy come over every week to clean his flat, he's not a ridiculous (and ridiculed) character. And Dudley getting involved with a witch makes so much sense from everything we see in (the latter stages of) canon.