At Lily's request, Albus Dumbledore has kept a secret from Severus Snape for 17 years. When Dumbledore learns that this secret plays a vital role in the war, however, it is Snape who is left to deal with the consequences. As Harry's true parentage is revealed, both his and Snape's futures become uncertain. The two must learn to work together in order to survive. PreHBP.