Harry Potter AU: Harry's Godmother

When Lupin gives Harry a tin of magical photographs of his parents and Sirius, one face sticks out to him. A mysterious blonde stranger appears in over half the photos, causing Harry to question why he's never heard of this woman. To his surprise, the woman his godmother, Tawny, and that his godfather, Sirius, was madly in love with her; and learns her impact on everyone's lives.