An excellent story! You weren't kidding when you said Harry was going to be fighting the odds. He already owes two favors to the Summer, and he has made an enemy out of Dresden, and we barely got started.
Your writing style itself is pretty goood, and it's fun to read. You seem to have Harry's (Potter) character down pretty well, albeit he is slightly overpowered. The best characterization has to be of Aurora's though. In the few lines she did have last chapter, you have her character down perfectly.
I eagerly anticipate what you do with this, so far, great story.
A few questions though, without giving too much of the plot away: Can you tell which Dresdenverse characters Potter will encounter? Perhaps Elaine, as she is involved with Summer.
And last... Is there a pairing in this?