Oh goodness, this is so inspired! Viktor Krum the gentlemanly math lover is supremely endearing. Love how you upend the Slavic Quidditch Brute cliché -- I would dig out my statistics textbook for a Quidditch ball with that one, and that says something.
I also love the three girls in the whirlpool and their Friday evening pastime. And while I haven't put a q.e.d. under anything resembling an equation in ages (and truth be told didn't miss it), I adore the math jargon! Then there are the many wonderful lines. Such as:
--"Seeking woman of mature years to help me milk my goats. Must have the initials P.S. Contact Aberforth D." --In her head, it was Pomona's voice that said international. --He slid her shoes off, and rubbed the arch of each foot. "This is heavenly," she said, (I concur!) --She passed through the icy essence of Myrtle, ignored her shout – "THAT'S RUDE!" – and swept through the office to pull open the door. --"This has been lovely, truly, but I will not date you if you are only interested in my . . . brains." --When she stared back with a raised brow, he added, "and we vill have lots of sex. And, last but certainly not least: --"PROFESSOR MCGONAGALL HAS A BOYFRIEND, A BOYFRIEND, A BOYFRIEND!"