Darn, I thought I had written you feedback for this gem, but no... Loved it absolutely! Millicent is one of my favourite characters ever, and this pairing is sort of a shining example of what 'rarepair' is able to do.
Both Millicent and Dudley feel perfectly in character, unprettified, not downright nice, but very likeable. And whacky as it is, the premise *works*, both having Dudley stomping into wizarding London, and having him lend a hand in spiffying up Millicent's flagging sex shop. The fun kind of whacky. Especially with the wizarding sex toys and McGonagall turning up, of all people! :)
And the pairing... they just feel right for each other (though you were a bit harsh there on poor Harry...). I also loved the ending, with Dudley moving towards self-acceptance. It sort of did him proud, and the entire fic, and the fest too. Brilliant job!