I'd suggest doing a prologue. Some scenes of Peter suffering, and his changes as a result.
Peter becoming the Recluse is the story, isn't it? As such, where are you starting?
I don't mind the idea, it could be interesting.
But, this isn't, yet, an actual story.
I look forward to the fanfic itself.
Edit: The Black Recluse is fine, as a bad guy name.