I am betting that he ends up being  Harrys new apprentice.

If Harry was going to get a new apprentice I sort of doubt that we’d be introduced to them in a short. Generally the shorts have small effects on the main series. Usually just a reference here and there that you can grin about if you’d read the shorts but if you haven’t won’t throw you off your stride for people who just read the books. I can’t imagine Jim is going to start Peace Talks with Harry having a new apprentice in tow that the book-only people have never heard of. Jim tends to build major characters, not just drop them in. Molly was introduced like 5 or 6 books before she became Harry’s apprentice.

I have to say, I really love the multi-layered nature of this story, with how the perspectives build on each other. Really amazing bit of writing, imo. Loved it, and it just made me want that Maggie/Mouse spinoff more than ever.