Whew! Excellent read! Portrait!Snape is made of WIN! He's just as good when he's alive, too, but there's something about him being trapped in the frame and shooing Potter off that just tickled me. Draco's wishes!!! That was too much fun. He's so *perfectly* selfish here. And Viking!Draco? *sporfle* Marvelous. As horrified as Draco was by the whole ordeal, I somehow imagine him being extra-appalled as he watched his effete little self turn into a Viking warlord. The sex scenes were great (yay Bottom!Snape) and I've never read 'docking' before, but that was way hot!
The thing I loved best of all though was how well you used the Norse mythology. Using the Nithstang (sorry, no special keys on my laptop) was brilliant, and the whole Dark Lord theme works so well with the mythology. I think I liked this version better than Voldemort. Great story!