I enjoyed this story for its character development (you present both Petunia and Severus in a way that makes them more understandable without necessarily making them sympathetic), but it's your world-building in the character of Wesley that I will remember most: he's an excellent device for measuring Petunia's growing comfort with the magic that makes her comfortable, and he's so well-realised as a person as to make him anchor this view of the Potterverse for me.
What you do with structure in this fic is excellent, and as soon as I saw the daisy with the lily and petunia, I knew—and I squeed.
I do love this piece for its exploratory elements and how they all come together in Daisy. :)