Well, you're not the first to do this, exactly. Skysaber has /The Wizard of Gotham/, where Harry's raised by Poison Ivy and that bunch. It's over on FF.net -- I recommend it.
Having said that, I really like the Society. An entire nest of supervillans with snake personae -- how cool is that? :)
So -- why wasn't Sssyrinusss used a little more? I hope to see more of the villians using Harry's parceltounge abilities in future chapters.
And what was the deal with Yaxley? A little from his POV would have been nice. Did he know the BWL was there? If so, how? What were his intentions? If not, just what was he doing there in the first place?
You're a little weak on description and emotion, though that will come with time & practice. Watch your spelling -- it's 'Kedavra', not 'Kendavra' -- though there were very few spelling errors, that was one of the more jarring ones.
I really enjoyed the story, though, and I hope to see more soon! Let me know if there's anything I can do to help you work on this.
Hary's just five at this point. As he gets older, the Taskmaster (and Emma Frost, if he doesn't go to Hogwarts) will help him figure out offensive uses for his 'mutant powers'.