A house-elf who served in the House of Black, Kreacher's loyalty to the Black family was absolute and undying. He also absorbed the anti-Muggle beliefs of the Black family.
Eventually, after being given back the locket that Regulus had switched for Voldemort's real Horcrux, Kreacher grew less hostile and was happier than he had been in many years, resuming most of his expected duties. He also led the house elves into the fray during the Battle of Hogwarts.
If he has passed into your ownership, he will have to obey. If not, then we shall have to think of some other means of keeping him from his rightful mistress." Kreacher: "Won't, won't, won't, WON'T!" Harry: "Kreacher, shut up!"
Kreacher, the house-elf of the Black family, was very loyal to Regulus, who always treated him with kindness. Kreacher respected Regulus very much, and he served Lord Voldemort when the latter asked Regulus to lend him a house-elf.
Though Kreacher seemed like a real baddie earlier on, it was actually just his loyalty to the house of Black that made him appear that way. And, when treated with an ounce of respect, he reveals himself to be a good little guy.
The Story of Kreacher (The House Elf of The Black Family)
Does Kreacher betray Harry?
Kreacher however sold enough information to get Narcissa knowing that Harry loved Sirius and would go to protect him from Voldemort in a possible hostage crisis. So, Narcissa told Voldemort of the information and he planted a false image in Harry's head, thanks to Kreacher's treachery.
A house-elf who served in the House of Black, Kreacher's loyalty to the Black family was absolute and undying. He also absorbed the anti-Muggle beliefs of the Black family.
Like his family, Regulus was easily swayed by Lord Voldemort's "pure-blood" rhetoric. He learned too late that the Lord Voldemort's beliefs were far more evil than he had ever realized and being a Death Eater involved far more unpleasantness than he was capable of.
In canon, Regulus Black didn't marry anyone. In fact, he wouldn't have had much chance to be in a long-term relationship, much less marriage, prior to his death. He was born in 1961, started Hogwarts the year after his older brother Sirius, became a Death Eater at sixteen, and died in 1979 at age 18.
Because Kreacher knew too much. When Grimmauld's place was the HQ for Order of the Phoenix's meetings, Kreacher was constantly in the presence of their plans and strategies. Freeing Kreacher then would've been a grave mistake.
Harry describes Umbridge to Sirius Black, saying that she's vile enough to be a Death Eater, despite not being one. Umbridge is also depicted to be a prejudiced person, despising half-breeds and Muggle-born witches and wizards to the point of firing Hagrid due to his half-giant birth status.
His life after the battle is unknown, although it can be assumed that he continued serving his master Harry, or perhaps he continued working in the Hogwarts kitchens. In 2017, J.K. Rowling revealed on X (formerly Twitter) that Kreacher died at the age of 666.
It's unknown what happened to Grimmauld Place when the Second Wizarding War was over, but even though Harry was not living in it, it's possible that it was kept safe for the Order of the Phoenix.
However, despite his best efforts, Kreacher was unable to destroy the Horcrux. He kept the locket in the Black family house, and both the real and fake Horcrux lockets lay undisturbed in their new hiding places for over fifteen years.
According to the WOMBAT test, it is possible that house-elves have an average life expectancy of 200 years, cannot be ordered to kill themselves, breed infrequently and only with their master's permission, can override wizard enchantments, and have an allegiance to their home rather than its inhabitants.
Sirius' love for Regulus is a VERY popular theme in Marauders-era fanfiction. However, there is nothing in the books to suggest he cared deeply, or at all, about Regulus.
Regulus was sorted into Slytherin and he became close friends with Barty Crouch. Jr. When Sirius left home, Regulus found Sirius's notes on becoming an Animagus, and he and Barty secretly became Animagi, themselves, with Regulus as a cat, and Barty as a weasel.
Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").
Early Life. Although Sirius was the older son and heir, Regulus's parents liked him more, as he upheld the Black family traditions and was loyal to his parents, although his brother Sirius didn't follow any of the traditions. Regulus is two years younger than Sirius.
Regulus Arcturus Black (1961 – 1979), also known as R.A.B., was a pure-blood wizard, born to Orion and Walburga Black, and the younger brother of Sirius Black. He attended Hogwarts School of Witchcraft and Wizardry in 1972 and was sorted into the Slytherin house.
Kreacher, a house-elf loyal to the House of Black, was the key to how Regulus potentially discovered the secret of the locket. From the book chapter "Kreacher's Tale" from the Deathly Hallows, it was known that Regulus volunteered the elf to assist Voldemort. Kreacher was used to test the defenses of the Horcrux.
Narcissa and Bellatrix were kind to Kreacher because he was very much loyal to them, he followed each and every order of them. Also, Kreacher was not a muggle lover or blood traitor. So, there was no reason ro be harsh towards him.
