'You must have killed him, didn't you?' Sirius hissed, kicking Kreacher to the ground and waving his wand.
"Crucius!"
In an instant, the spell's beam struck Kreacher, and the elderly house-elf let out a blood-curdling scream and began to writhe on the floor.
Nobody else in the room saw Sirius's outburst coming,
"Are you mad? Sirius!" Without hesitation, Lupin rushed forward to stop Sirius from torturing Kreacher any further.
'Let go of me and I'll teach it a lesson today!' Sirius's eyes were red with rage and he tried to break free from Lupin.
Afraid to harm Sirius, Lupin tried to force him, but Sirius punched him in the stomach.
After freeing himself from Lupin, Sirius took a few steps forward, his eyes bloodshot, and waved his wand at Kreacher again, shouting.
"Powdered body…"
"Expelliarmus!"
Sirius was halfway through his incantation when another voice spoke.
A red beam of magical light flashed past, and Sirius was thrown back against the wall as if he had been hit, his wand flying out of his hand and spinning into Ivan's.
Yvonne took the wand from him, but not without caution, as Sirius was not himself.
It did not take long for Ivan to guess that Sirius was under the influence of a Horcrux, and he shouted to Lupin and the others.
"Quick! Take the locket from him!"
Lupin, having recovered from his shock, lunged at Sirius in an attempt to seize the Horcrux.
However, the latter seemed to have lost her mind and desperately tried to protect the locket in her hand. The two of them wrestled and the locket fell to the ground with a soft sound.
Harry took the opportunity to pick up Slytherin's locket and throw it back at Ivan.
Just as he was about to let go of the locket, however, Harry stopped short, as he felt a stabbing pain in the scar on his head.
Luckily, Ivan stepped in and took the Horcrux, allowing Harry to regain his composure.
"Come to your senses, Harry, are you all right?" Yvonne asked, looking worried.
Harry shook his head to show that he was fine, apart from the pain in his scar, and then, remembering Sirius, ran to him, worried.
The Horcrux quivered uneasily in Ivan's hand, and Ivan was vaguely aware of an intrusion into his brain. He instinctively activated Occlumency, and the feeling quickly disappeared.
Apparently, Occlumency at Level 6 was quite powerful, as Horcruxes could not affect him.
Sirius, now under Lupin's control, was now back to normal. He clearly remembered all of his actions, but they seemed so foreign to him…
"I'm sorry, Lupin… I don't know what happened, but I hope I didn't hurt you," Sirius apologized to Lupin, looking awkwardly at Harry and Ivan.
"That was quite a punch! But I'm not that weak!" Lupin teased, not caring about the incident.
Lupin's gaze then returned to the Horcrux in Ivan's hand, and he continued confidently, "It would seem that this locket affected your emotions…"
Sirius and Harry looked over as well.
"Yes! Lupin was right. It affects the mind. Professor Lockhart was killed by the same thing when he was in school!" Ivan explained as he fiddled with his Horcrux.
As far as he knew, every Horcrux created by Voldemort possessed the ability to bewitch the mind.
Based on the time of Regulus's death, Slytherin's Locket must have been a Horcrux created by Lord Voldemort in his prime, much more powerful than the Diadem and Diadem, in order to affect Sirius without his knowledge.
This, of course, had something to do with Sirius losing control of his emotions after hearing about Regulus, and the Horcrux only inflamed his emotions, driving him mad.
'It's too dangerous, we'd better destroy it now!' Sirius said solemnly, still fearful of the evil thoughts that had come to him.
Ivan nodded. Destroying Horcruxes was not difficult for him, and it was not the first time he had done so.
"But I think you forgot to apologize to the other one!" Ivan said, looking at Kreacher, who was trembling on the floor.
"Kreacher was a bad elf… Master Regulus should not have died… Kreacher should have died…" The elderly house-elf cowered in the corner, murmuring to himself, tears and snot running down his face.
'You mean you want me to apologise to Kreacher?' Sirius frowned, sounding reluctant.
"Sirius, I also think you should apologise, you nearly killed it!" Harry tried to help him, looking at the poor house-elf lying on the floor with sympathy.
"Kreacher didn't do anything wrong, did he? He did his best to do Regulus's bidding, and he was a wonderful house-elf!"
'Come on, you've probably forgotten how it used to call you guys!' Sirius pursed his lips, still looking at Kreacher with displeasure.
Sirius couldn't understand why Regulus would choose to drink the potion himself, when Kreacher could have done it himself, as long as the Inferi didn't wake up.
Thus, there were some complaints about the house-elf, Sirius, regarding his inability to protect his brother…
Ivan shook his head to himself; he could, of course, read Sirius's mind, and, more importantly, he could see the humble status of house-elves in Sirius's reaction.
Sirius was willing to apologise immediately to Lupin for the punch, but not to Kreacher, whom he had almost killed.
This was not because of his character, but because the many years of lessons he had learned had unconsciously shaped the views of most wizards. House-elves were like slaves to them, and they could be killed at will.
Why would a master apologize to a slave?
(PS: Special reasons. Sorry for the day's delay. Please understand.