Kreacher knew. He knew about the Goblin Wars, about group oaths, and about the role of a guarantor in them. It was an enormous responsibility and a comparable power. According to the house-elf, the guarantor's word was backed by the magic of all the groups involved—yes, there were sometimes more than two—for whom he mediated, and it could practically move mountains. Breaking a group oath always brought serious consequences for the violators, so the elf emphasized that the master should be careful and considerate with every word, not to mention every action. Otherwise, abusing the guarantor's position would backfire on him, leaving not even a trace of him.
This was believable, given that Voldemort had disincarnated when attempting to kill an infant, leaving only a handful of ashes behind. Apparently, he too had broken something... something very serious, since there was no maternal sacrifice as Dumbledore claimed. When Arcturus asked the house-elf what this might have been, he replied that the dark wizard had made an oath to his followers to protect their interests, and the child was the adopted son of one of them and had not acted against them first.
Why hadn't Kreacher mentioned this before? No one had asked him.
He brought Arcturus a pile of historical notes and painstakingly went through each case with him, explaining the weight of each word in detail. After all, magic was nothing more than a formulated intention that wizards could empower, unlike empty-talking Muggles. Arcturus was horrified at the consequences of uttering "may it be so," "may you be," and "may I be" carelessly, after reading how these words could manifest when said with conviction—with force.
For the first time, he realized just how much he lacked self-discipline and self-control. He had a lot of work to do on both.
By the appointed time, Arcturus knew what he was getting into. He was not going to back down and made sure everything was done in the best way possible. There were no universal formulations for group oaths, so he had prepared several versions of the oath in advance and could explain the features, drawbacks, and merits of each. Unlike personal oaths, which could do without a magical witness, a witness was mandatory for a group oath, and Arcturus informed Narcissa of this in a letter.
In addition, items representing the parties to the agreement were required—usually small valuables that could be held in one's hand during the oath. Arcturus settled on semi-precious stones, initially considering marble for the Ministry's side and onyx for the Death Eaters, but Kreacher noted that color wasn't so straightforward and suggested two jaspers in different shades.
At the next meeting, Arcturus discussed the oath options with the Death Eaters. Together, they chose the most suitable option and then a secondary one, in case Shacklebolt flatly refused the first. Seeing that the young man understood the topic, the fugitives trusted him to work out the details and decide on the final formulation himself.
Meanwhile, Narcissa was negotiating with the minister, displaying a charm and diplomatic skill beyond belief. Shacklebolt was distrustful and suspicious, making progress slow. At first, he refused to consider anything, rebutting all her arguments with an outraged "but they're Death Eaters!"—yet, as the saying goes, water wears away the stone, and he was personally interested in the matter. Little by little, Narcissa managed to convince the stubborn man that all the evil stemmed from the Dark Lord, that his Mark, which he had deceived the Death Eaters about, had enslaved them, and that no one would have come up with such things on their own. Now they were all repentant and thus not dangerous. They were hiding from the law because they feared no one would believe them.
Eventually, Shacklebolt agreed. Not to an oath, but simply to accept and listen to the mediator—Narcissa's nephew, who, she assured him, had no connection with the Death Eaters. Narcissa immediately informed Arcturus in a letter and brought him to St. Mungo's.
The young man—quiet, polite, respectful, slightly timid—made a favorable impression on Shacklebolt. Favorable enough that the minister unknowingly began to listen to his suggestions without prejudice. This Travers-Black fellow filled his speech with historical examples, showing how a magically bound pact for peaceful coexistence had ended even the longest, most bitter conflicts, including those between people and goblins. When Arcturus finally stated that if magical commitments could bring peace between humans and goblins, they could all the more easily bring peace among humans, Shacklebolt seriously considered the proposal and carefully read through the texts of the proposed oaths of truce.
"This one will do," he pointed to the second version. "It's almost suitable, except for the clause on accountability for violations."
"What's wrong with it?" Arcturus asked, expecting objections on entirely different points. "That's a standard clause in such oaths."
"What does 'indirect punishment' mean here?"
"It means that a violation of the oath by any party's representative constitutes a state crime and should be prosecuted in the proper governmental bodies."
"So, violators bear no magical responsibility, unlike in personal oaths? No, that won't do. I know these Death Eaters, give them an inch, and they'll cause trouble. The accountability must be magical, Mr. Travers—they're claiming to treat people, so I must take precautions."
"This will be a very strict oath," Arcturus warned. "Knowledgeable people worked on this wording; they didn't make this clause as it is without reason."
"But they're Death Eaters; they can't be treated any other way. Let them think twice before attempting to harm people."
Arcturus knew that the former Death Eaters had no intention of causing harm. At least, they had told him as much, and it didn't seem like a lie. But if it was a lie... they would learn that one doesn't lie in matters like these. However long the truce oath would last—a week or two, until Rabastan cured the affected of the curse—a magical peace treaty with different terms would be signed by then. The minister's amendment equally applied to both sides, so it was more in the fugitives' favor than not.
"If you insist, sir..."
"I do insist."
"Then we can rephrase this clause similarly to a personal oath—'direct punishment in the form of magical backlash.' Will that work?"
The minister reread the clause with the modification in mind.
"It'll do."
Arcturus touched his wand to the parchment, amending the text. Shacklebolt reread it and agreed to the oath. Both jaspers were kept around Arcturus's neck in a pouch on a cord Kreacher had provided him. Arcturus poured them into his hand, chose the stone engraved with "MM" for the Ministry of Magic, and handed it to the minister. The second stone, engraved with "VR" for the Knights of Walpurgis, he held in his right, wand hand.
Shacklebolt took the stone but looked at it in puzzlement.
"What's this for?"
"What do you mean?" Arcturus realized that this upstart minister from the lower ranks, barely appointed, had probably missed or skipped the Hogwarts lecture on oaths. But it wasn't his duty to educate him, so he simply said, "These stones make me the guarantor of the truce."
These stones served as conduits for the magic of the contracting parties, granting the guarantor invulnerability and power. Historically, guarantors had used this power to prevent skirmishes and brawls during negotiations, at which they were always present.
"Well, if they do..." Shacklebolt turned the stone in his fingers. "How does it work?"
"Hold it in your hand along with your wand while sealing the oath. Then you'll return it to me." Arcturus turned to Narcissa, who was accompanying him. "Lady Malfoy, bear witness to the oath."
All three drew their wands from their sheaths. Shacklebolt and Arcturus crossed their hands, each holding a wand and a stone, and Arcturus spoke:
"I, Arcturus Procyon Travers-Black, independent guarantor of the truce between the British government and the opposition known as the Order of the Knights of Walpurgis, also called the Death Eater clique, swear by my magic to impartially oversee the oaths and ensure the parties uphold the truce terms. So be it."
When he finished his oath, it was the minister's turn.
"I, Kingsley Shacklebolt, Minister of Magic of the British state, on behalf of its citizens who have entrusted me to represent their interests, swear by my magic..." He then began reading the oath from the parchment, as it was long, nearly filling the entire sheet.
"I bear witness," Narcissa murmured, moving her wand, and a transparent ribbon of oath confirmation wrapped around their clasped hands.
"When will these Death Eaters start the healing?" asked the minister as Arcturus put both stones back in the pouch.
"First, I will obtain their oath of truce," Arcturus replied. "Rest assured, it will be exactly the same; I swore to that by my magic. The purpose of the truce, as you know, is to allow the warring sides to negotiate the terms of peace. On the Death Eaters' side, it is the healing of those affected by the dark magic epidemic and the complete cessation of terrorist activities. On the British government's side, it is an amnesty for crimes committed within the organization's activities. When their current leader swears the oath, I will inform you, and you can begin negotiations. Once terms of peace are agreed upon, the Death Eaters will begin healing as per the agreement. Additionally, you will order announcements about the truce in the press and on the wizarding radio within three days. This will help prevent conflicts, as the former Death Eaters will need to appear in public."
"I'm afraid the people won't understand," Shacklebolt muttered unhappily. "Perhaps we should keep it a secret for now?"
"No, we can't do that. The people must get used to the idea of peace, or it will be worse. Historically, surprises like this have often led to mass violence, so be sure to announce sanctions for violating the truce."
"Maybe you're right…" the minister acknowledged after some thought. "But it would still be better if their leader came to me under disguise. Who is he, by the way?"
"Rabastan Lestrange."