Character from harry-potter-deathly-hallows by
Ancient Black family house-elf transformed by a single act of kindness -- Harry gave him Regulus's locket and treated him with respect, and Kreacher repaid it by leading the house-elves of Hogwarts into battle.
Kreacher is living proof that how you treat the powerless defines who you are. For years he was a bitter, racist creature shaped by decades of the Blacks' pure-blood ideology, hoarding family relics and muttering slurs. He betrayed Sirius. He was horrible. Then Harry gave him Regulus's fake locket -- the one Regulus substituted for the Horcrux before dying in the cave -- and asked about Regulus's story. Harry listened. He treated Kreacher like a person. And Kreacher transformed. He started cooking. Cleaning. He began wearing the locket like a medal of honor. He helped track down Mundungus Fletcher and the real locket. He called Harry 'Master' not with servility but with genuine devotion. During the Battle of Hogwarts, Kreacher leads the house-elves out of the kitchens and into the fight, hacking at Death Eaters' ankles and screaming 'Fight! Fight for my master, the defender of house-elves!' It is absurd, it is glorious, and it is everything Hermione's S.P.E.W. campaign tried to achieve through legislation that Kreacher achieved through being seen as worth seeing.
Elderly, stooped, bulging pale eyes, snout-like nose, white hair sprouting from bat-like ears. Now wears a clean loincloth and Regulus's locket with pride. Stands taller than before. Still mutters, but the insults have stopped.
Also known as: Kreacher