This is wonderful. The people are all so in character. Hermione and Harry talking and drinking are so beautifully homelike, just the kind of lifelong friendship you'd want to have. Especially with the crup and the kneazle and the kitchen spells and the husband who grins when he finds them passed-out drunk.
The children are wonderful; Kreacher and the senile furniture are awesome; the perfumes are wonderful new magic.
And this: Snape was far from handsome, but he had terrific presence. His apparent ferocity overlaid a repressed sensuality that Snape might not even realise he possessed.
Ahhh! Not just a wonderful 1st-time story (and not unrealistically fluffy and fast, either), but one that cuts straight to the heart of Severus Snape's attractiveness. It's so lovely that Harry, grown up, a caring man and father, recognizes this!