Stunningly brilliant. This Muriel is so perfectly canon, and so perfectly Muriel. Even the accountant / possible squib Ron once mentions is in. Your cameos - of Molly, of Luna, of Wilhelmina, of Bella, in all its chilling madness, are to die for. I'm fascinated by the wandlore, that fits and expands so perfectly what we know from canon. The way wands can stop functioning for you, when you change. Things that change deeply enough for that to happen.
The story of Muriel's life, and of Ollivander himself.
And above all, the way they come together in that continuous game of chess. And the sexscene is the best I've ever read.