Regulus Black is the second son of Orion and Walburga Black and the younger brother of Sirius Black. He attended Hogwarts between 1972-1979 and was sorted into Slytherin house. He is married to Marlena Black who is the mother of his three children. He was trained as a mage alongside his wife and several friends. During this time, his doppelganger joined the death eaters as his parents' insistence. When he returned to wizarding society, Regulus and his wife faked their deaths and left Albion.
He was the younger brother of Sirius Black, but their parents always favored Regulus. Unlike his brother, he was polite, respectful, and mirrored their parents' pure-blood beliefs.
When he arrived at Hogwarts, Regulus was sorted into Slytherin house, pleasing his parents. He befriended many of the people in his house, but he also made friends with people in other houses whom his parents weren't pleased with. Chief among them was his future wife, Marlena McKinnon.
In his fifth year, he got his then-girlfriend, Marlena McKinnon, pregnant. As they were both nobility, their parents insisted they be married immediately.