Your story crept up on me gradually without my noticing it. So when I got to the challenge between Bane and Dudley, I was genuinely worried, and I realized that I cared about these people (err, beings?) enough to be afraid for them.
I also laughed in a number of places. Having the patonus take on the drunkenness of its caster was a really creative touch. And drunken Harry, oh my. He's lucky Ginny thought it was funny.