Harry Potter and the Noble and Most Ancient House of Black (джен)

Regulus hadn't met his end in the cave as most expected. He had everyone fooled, including his mother, father, and even brother. Kreacher, the black family house-elf, had saved Regulus but, in turn, traded Regulus's fate for his own. Regulus would never forget his sacrifice for the young master.
Regulus never wanted to become a death eater. He found himself similar to his brother but had the brains not to voice it out loud, especially after he was condemned as the spare when Sirius was disowned. Walburga took no time to ensure Regulus couldn't leave like Sirius, and Orion did nothing but watch as his son was branded by the dark lord.
In 1979, Orion had been murdered by order of the dark lord while he and Kreacher went to hide Slytherin's Locket. Regulus had seen it with his eyes, and he had been the reason. He'll never forget Walburga's screams of anguish as she realized what her son had done. Screaming and screaming. She wouldn't hear that Regulus was under the Imperius curse. She thought he'd turn out just as rotten as his older brother. In a way, she was correct.