Oh, this is amazing. Not all Minerva/Severus grabs me, but this one certainly did.
I absolutely adore the sense of place and character in this - the little town, the small cottage and the quiet air, mirrored by the two characters who are fairly contained and quiet themselves. The book-end style passages about the children are magnificent, capturing the essence of the story wonderfully. I particularly like the fact that Mikey emerged with a piece of toffee.
Severus as a little black tom is fantastic, and so realistic. I love the reconciliation, the description of cat movement and affection (I see it a lot at home). His mannerisms, both in cat and human form, are fanastic, as is his first-time with Minerva.