The Woods are Lovely, Dark and Deep (I have promises to keep)

Prompt fill for Anything But Human Fest:

"Lost in the woods surrounding their secluded village, James and Lily are found by the monstrous forest god Voldemort, who leads them back to safety in exchange for their firstborn child. When Harry is born they don’t give him up, and figure they’re safe as long as they keep away from the woods, as its creatures are somehow unable to leave. But even if V is unable to physically reach them, his powers manage to drain their lives before Harry turns two.
Being raised by the Dursleys, Harry grows up strangely fascinated with the forest, even if he knows he must never enter its domains (surprise: he ends up doing it)"