There is too much to love about this. Absolutely brilliant!
This should become an instant classic Snarry fanfic qoute: "Snape had risen to his feet and parted the placket of his trousers, pulling forth a truly monstrous specimen of virility."
I sure hope it's ok that I not only pictured this as Sherlock Holmes, but at the same time as a good bit of Johnny English. Which made me giggle like mad while reading it. I think that was mostly due to the contrast of Harry's narrated part and the "actual" happenings around him. That worked brilliantly, in my opinion.
To say I loved this would be quite an understatement.