Chapter 66:
Sirius looked angry again, but before he could lash out, Harry intervened.
"Hello, Kreacher, my name is Harry. I suspect you feel the bond because I'm the Black family Heir," he explained.
Kreacher looked startled and pulled his ear. "Halfblood Heirs, wolves, what is next for poor Kreacher?" he muttered.
"You're right, I am a halfblood and I was even raised by awful muggles. Muggles who hurt me," Harry said.
Kreacher stilled then. "Muggles hurt little Heir?" he asked.
"Yes, that's why Sirius became your new Lord. We are going to live here from now on and he is going to help me to get better," Harry said, looking at Sirius when he went to interrupt Harry's lies.
Kreacher looked indecisive before he nodded. He could feel the boy's power as it called to him; he was strong and Dark. The power was intoxicating. If this boy was the Heir to the Black family, Kreacher would be happy to help him and their magic was already bonded, anyway. Kreacher was confused - his boy was his Lord but not his Lord. "Kreacher is happy to serve new Lord Black if he is helping Little Master," Kreacher said. "Little Master should have never been with nasty muggles. Bad things. No, Little Master should be here with Kreacher. Kreacher will look after him, help him. Yes, Kreacher will serve," the elf muttered.
Harry smiled and sent Sirius a smug look. Sirius was floored - the elf never listened to anybody other than his mother and Regulus, who he adored. He had always hated Sirius, even when he was a child.
"How?" he asked Harry when the elf popped away. Harry had used their shock to ask for the locket, promising to destroy it when he could. Harry shrugged. "I'm just that good," he deadpanned.
"No, seriously. Kreacher hates me," Sirius said, still bewildered, "and here he is, willing to serve me just because of you. He's just met you."
"Maybe he liked the feel of me through the bond?" Harry suggested.