The Noble House Black.

Leonidas Black is the only child born off of Sirius Black and his wife Emily Potter. Born only days before his cousin Harry, Dumbledore knew that the prophecy could speak about three boys The Potters where in hiding and so was the family Black, with the Potter's dead.... and no one Albus trusted the boy with there was one who stepped forward to raise him as his own, to teach and protect him and that person was Minerva Mcgonagall.