One for Sorrow

This is the first Life Debt theory I've read that makes perfect sense to me. I've always been puzzled about why certain life-saving actions produce a life debt and others don't, but this explanation is perfect, and very Potterverse (i.e. slightly mean-spirited but not nonsensical). But it's not just how it works in your theory, but your description of what could be done with it that makes it so fabulous - there would be a point to its existence, which I don't think is there if all it does is lead to Snape dying for Harry. Thank you!