The Death Debt

Severus Snape now owes James Potter a Life Debt, an ancient magical binding made from Light magic. But there is a lesser known binding, one of a much Darker nature, called a Death Debt. An attempted murderer who fails to deliver a soul to Death must repay Death with another soul, one chosen by their intended victim.

Severus is not going to let such an opportunity slip him by. He will bind Sirius to him and make him fulfill his end of the Death Debt. And Severus's chosen victim? Tobias Snape.