However, Sirius was not the only child of his parents, Walburga and Orion Black. He had a younger brother called Regulus Black, who became an unlikely crusader against the Dark Lord. Regulus Had ...

So, who is R.A.B.? As Harry and his friends eventually learn, the locket belonged to Sirius' brother Regulus Arcturus Black, who, keeping with the Black family tradition, valued pureblood lineage ...