I really liked the weekly progression of this: how we learn important backstory a bit at a time, how Harry and Severus' relationship unfolds, how we're along with Harry in resolving the mystery. The idea that Voldemort could return and Harry's scar was a signal is just chilling, so I can understand completely why he'd agree to the soul bond. And the outcome, when Severus and James assess each other so carefully, seems to worked out well.