The Youngest of House Black

Irina "Iris" Black was raised by her godfather, Remus Lupin. She had never met her father. Now, Iris is off to her first year of Hogwarts. She becomes friends with the Golden trio, The Weasley twins, Ginny and Neville. But when Sirius Black is on the loose, Iris has this feeling that she is the Prisoner of Azkaban's daughter.

Takes place during "Harry Potter and the Prisoner of Azkaban" and "Harry Potter and the Goblet of Fire".
(Iris and Jack are the only characters I own. The rest are Harry Potter characters.)