Slytherin's Locket?

Two suits of armor appeared. One subdued Sirius Black, while the other snatched the Small Golden Box away.

Vizet aimed his Wand at Sirius Black and traced a smooth S-shaped arc through the air. The Obscurus Core pumped out Ancient Magic Power. "Dust and Grime Begone!"

The sudden restraint, the Small Golden Box leaving his hand, and Ancient Magic: Purifying Cleansing Soul Washing Spell all made Sirius Black calm down. He turned to look at Kreacher, who had fallen unconscious on the floor.

"What was I..." The armor loosened its hold and stood in place. Sirius Black's voice held a touch of disbelief. "What happened?"

"Was it because of this?" He turned to look at the Small Golden Box held by the armor. "Just now, I felt like... I couldn't control myself. Whatever I wanted to do, I just did..."

"I think so..." Vizet walked out of the room and waved his Wand to make the standing suit of armor follow. "Didn't something similar happen to Kreacher too?"

At his command, the armor strode forward quickly and carried Kreacher over to a nearby table.

Sirius Black followed as well. "Vizet, how is he?"

Vizet waved his Wand and scanned it over Kreacher's body. "His body is still very sturdy. He's only unconscious, that's all... Dust and Grime Begone!"

He cast Ancient Magic: Purifying Cleansing Soul Washing Spell again, helping Kreacher remove the evil thoughts from his body too.

"What exactly is this thing?" Sirius Black looked at the Small Golden Box again. "Judging by this style... it shouldn't be something from the Black Family, but it should be just as ancient."

Vizet gave his Wand a light flick, making the armor present the Small Golden Box in front of him, and carefully examined this strange Dark Magic Item.

This