Slytherin's Locket

"He looked at the serpentine S, inlaid with glittering, green stones: It was easy to visualize it as a minuscule snake ... concentrating on the letter S, imagining a serpent, while the contents of the locket rattled like a trapped cockroach. It would have been easy to pity it, except that the cut around Harry's necks still burned [...]The golden doors of the locket swung wide with a little click. Behind both of the glass windows within blinked a living eye, dark and handsome as Tom Riddle's eyes had been before he turned them scarlet and slit-pupiled."

"To the Dark Lord
I know I will be dead long before you read this but I want you to know that it was I who discovered your secret. I have stolen the real Horcrux and intend to destroy it as soon as I can. I face death in the hope that when you meet your match you will be mortal once more.
R.A.B."

Late in the 1970s, Lord Voldemort requested the use of a House-elf from hisDeath Eaters.A young Death Eater, Regulus Black volunteered the Black family house-elf Kreacher, whom the Dark Lord used to test the locket's defences. When he had seen the cave's effectiveness in action, he left Kreacher to die on the island in the middle of the dark lake. However, he overlooked the house-elves' special magic binding them to their masters, considering it beneath him and not of importance. As Regulus had instructed Kreacher to do all that Voldemort asked of him and then return home, Kreacher was able to Apparate out of the cave and back to his master Regulus. The younger Black was infuriated at the mistreatment of Kreacher, and having seen the lengths to which the Dark Lord would go, turned against Voldemort.