Sirius Black Kreacher resented Sirius because of this treatment, and he later betrayed Sirius by telling Bellatrix about how she could exploit his close relationship with Harry, eventually resulting in Sirius' death.
This in turn comes back to haunt him, as Kreacher eventually betrays Sirius to Voldemort, leading to Sirius's death.
Who is most to blame for the death of Sirius Black? Bellatrix Lestrange pulled the trigger, so she is the one most to blame for murdering Sirius, and she works for Voldemort—he shares the blame for every crime committed by his minions.
Kreacher disliked Sirius because Sirius thought differently to his ancient family, and Kreacher had the same views as his masters and mistresses. He couldn't think for himself, and that's where he and Sirius were so very different. Kreacher was mistreated by Sirius for many years because of this.
Sirius makes the fatal error of underestimating Kreacher. Believing him unable to leave Grimmauld Place except on his orders, he doesn't realise that an angrily bellowed order of 'Out!
Kreacher was not however fully able to betray the Order because he wasn't their protector and couldn't say where the House of Black was. 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.
After Sirius' death, Harry Potter became Kreacher's new master. Kreacher disliked Potter and neither did Potter like Kreacher. When Albus Dumbledore came to Privet Drive to tell Harry what Sirius had left him, which included Kreacher and Grimmauld Place Twelve and all his belongings.
The Black family elf Kreacher did not have any love for many people other than his master. However, as hateful as she is to most people, Bellatrix was always very kind to Kreacher. In fact, Kreacher even kept a picture of Madame Lestrange by his bed because of how kind she was to him.
Kreacher's joy at being given a Black family "heirloom" as his own caused him to drastically change his view of Harry. He even started to treat Hermione, whom he had previously disdained as a "Mudblood", a bit better. Hermione turned out to be right about Kreacher; he was nice to those who treat him well.
Sirius insisted that Kreacher could not be set free because he, Knew to much about the order. Fred & George were shocked when they found out that, Ron had been made prefect & Harry had not.
In the final cut of the movie, Harry's scream is muted entirely. According to director David Yates, he wanted to slow the scene down to allow the audience to allow themselves to process the death without interruption.
Upon the dais is a stone archway, covered with a tattered black veil. Sirius is hit by Bellatrix's curse, and his stunned body arcs into the air and floats through the archway, disappearing behind the veil.
In the film, Bellatrix hit Sirius with the Killing Curse, Avada Kedavra, killing him before he passes through the Veil. In the book, the curse that hits Sirius is not identified (although it is rumoured to be Stupefy because of the red light), and him being knocked through the Veil is what causes his death.
Because he owed no loyalty to Harry, he was under no obligation to tell Harry anything, and Harry had no right to question him. Kreacher had to obey Sirius, but he didn't have to like Sirius at all.
Master Regulus volunteered Kreacher to assist Voldemort who then took Kreacher to a cave, forced him to drink a basin of burning potion and left him for dead. The elf had been used to test the defences for a locket bearing the symbol of Slytherin. Unbeknown to Voldemort, Kreacher escaped and returned to Regulus.
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.
Dumbledore seemed to have terrible nightmares or visions, and was almost too weak to stand up after drinking the potion. Kreacher said that when Voldemort forced him to drink the emerald potion his "insides burned" and he saw "terrible things" (DH10).
The potion, (the same one Dumbledore drank) caused Kreacher to have nightmarish delusions, intense stomach pains and made him dehydrated. Voldemort then left, leaving Kreacher to drink from the lake (as any water conjured evaporates) and die at the hands of the Inferi.
She married Rodolphus Lestrange after leaving Hogwarts "because it was expected of her" to marry a pure-blood. However, Rowling stated in an interview that Bellatrix truly loved Voldemort.
As Kreacher was not the Secret Keeper, he couldn't have given the location of the Order's HQ to either Bellatrix, Narcissa or anyone else. As Albus Dumbledore was the Secret Keeper to 12 Grimmauld Place, only he would be able to divulge the location.
We have learned that a House-Elf can be freed if given clothes by his or her master, but Hermione is not their master, and so accepting clothes from her will not free the elves.
Why didn't Regulus Arcturus Black made Kreacher drink that potion in the basin? Kreacher was powerful enough to absorb its effects and could apparate them both out of the cave.
Kreacher longed to be with Narcissa Malfoy and her family because they treated him better than Sirius. Kreacher hated Sirius, because Sirius hated the last living memory of his awful family life. Kreacher insulted Sirius many times after his murder.
Sirius Black
"Come on, you can do better than that!"