In this world, the meaning of a contract is different.
If even non-sentient beings can receive "divine protections," then the concept of a contract itself carries a kind of hidden blessing—the recognition of the world.
In other worlds, when you sign a contract with someone, even if it is written in black and white, breaking it merely requires paying damages or other penalties specified in the agreement. But in this world, contracts possess an inherent, compulsory power.
For example:
The contract between Puck and Emilia states that once Emilia dies, Puck will begin destroying the world.
The contract between Echidna and Beatrice is to guard the Forbidden Library until "that person" arrives.
The contract between the many "Ryuzu Meyer" clones and Echidna is to obey any command from the Witch of Greed—and her apostles—without condition.
These are all contracts, all possessing binding force. This compulsion can be understood as the will and rules of the world itself, and for most people in this world, it is something they would never question.
Just as hardly anyone on Earth questions why the planet revolves around the sun, for the inhabitants of this world, such things are simply accepted as natural laws.
At the moment, what Echidna was talking about—being her "advisor" or "accomplice"—sounded appealing. But Lillian was not foolish enough to agree immediately in a moment of excitement. He still remembered Ryuzu's words: "Don't think too kindly of the Witch."
"From what you're saying, it sounds like I'm the one benefiting," Lillian said, studying her and trying to discern the meaning behind her words. "If a contract is an equal exchange, then what do I have to give in return? If I gain all the knowledge and assistance of the Witch of Greed, what exactly am I offering in exchange?"
Hearing this, Echidna raised a single finger.
"There is only one thing. I wish to see other worlds as well. Beyond that 'modern world' and this one, I want to witness other worlds. That is all."
"…."
She appeared sincere, yet Lillian could not understand. How would she see other worlds? Would she try to force her soul into his mental space, like Betelgeuse once did? The only outcome of that would be the same—being burned to ashes by the flames of the goddess's consciousness.
Even if he traveled to other worlds in the future, how could she accompany him? If he made a contract with her and later failed to fulfill it, would he be punished by the laws of this world? Or would the existence of the "goddess" render such binding rules ineffective?
"What are you hesitating for?" Echidna tilted her head and looked at him gently. "If you form a contract with me, you can save the person you wish to save."
That was true. With her superhuman level of understanding, if he could return to the world of AOT in the future… if he gave her the injection, she might be able to decipher its secrets and produce an antidote.
"I…"
The words "I agree" hovered on his lips. Yet under Echidna's expectant gaze, Lillian swallowed them.
"There's no need to rush," he said.
"…That's true." A trace of disappointment flashed across Echidna's face, though it quickly vanished. The next moment, however, she suddenly added, "But you should decide soon."
"What?"
"You are not my only candidate." Echidna sat back down gracefully, lifted her teacup, and took a small sip. "There are others among my potential contract partners."
"…Natsuki Subaru?"
"Correct." Echidna's smile was mischievous, like that of a child plotting a prank. "Infinite return—doesn't that mean limitless opportunities for trial and error, and endless acquisition of knowledge? Oh, and that child is currently rushing here as well, eager to find answers and a solution to the crisis. Incidentally, the crisis you're both facing comes from the same person—my student. He really does enjoy causing trouble."
Wait.
At the mention of Roswaal, Lillian suddenly realized something and looked at her suspiciously.
After all, Roswaal's actions followed the guidance written in the Book of Wisdom—and the contents of that book were determined by Echidna herself.
Lillian suddenly felt that everything had been guided to this point by her hand, and his mind gradually calmed. Roswaal wanted to isolate Emilia—was that also Echidna's intention? Perhaps. But if her true target was not Emilia, but someone else—such as himself or Subaru—then what she wanted was likely for them to seek her help, allowing her to naturally form a contract.
At that realization, a chill ran through him. His attitude toward her shifted slightly. After a moment's thought, he suddenly said:
"I want to challenge the second trial."
"…Hm?" Echidna did not understand why he brought this up so abruptly.
He continued, "But this time, I don't want to ask any questions. If I succeed, I want an exchange."
"An exchange?" Echidna smiled faintly. "Why should I agree to that? Your challenge is not for my sake."
"Is that so? In truth, you also want the Sanctuary to be liberated, don't you?"
After Lillian spoke, the girl calmly asked, "Why do you say that?"
"I don't know the details of what happened hundreds of years ago, but this barrier certainly isn't only meant to restrict half-bloods. If I had to guess—you yourself cannot leave this place either. Why would Roswaal attempt the trial even at the risk of serious injury? Even if he's insane, he's an intelligent kind of madman. He wouldn't do something that yields no benefit—unless it was for his 'teacher,' making a rare irrational choice."
"For hundreds of years, no one has passed this trial. Its difficulty is obvious. Will you keep waiting? Or do you intend to rely on someone like Natsuki Subaru, who can revive endlessly, to pass it?" Lillian paused. "That won't work."
"Won't work?" Echidna sensed the implication. "What do you mean?"
"Because I have a hundred ways to make sure he dies—to prevent him from approaching this place. Your abilities only function within the tomb, correct? So, will you continue waiting? Waiting for an unknown amount of time to pass?"
The conversation fell silent.
Only the sound of wind sweeping across the hills echoed in the air.
After a long while, Echidna let out a soft sigh.
"I'm being threatened."
Lillian remained silent. He did not feel at ease leaving this crisis unresolved. Even if Subaru could ultimately overcome it, who knew how many returns it would require? He did not want to waste that much time waiting.
"What do you want in exchange?"
"After I complete the second trial," Lillian said, pulling the Gospel from his chest, "I want you to alter the contents of the Book of Wisdom in Roswaal's possession."
"…."
"How you change it is up to you. Just make sure he stops doing things like using climate magic. For you, that should be a trivial matter, shouldn't it?"
"To alter its contents, you say. Do you know, Lillian," Echidna said, calling him by name—something she rarely did, "the Book of Wisdom gathers an enormous amount of knowledge. Once given a purpose, it automatically calculates how to achieve that goal. The calculation produces an 'optimal path,' and that path is what appears in Roswaal's book."
"If I were to alter it, I would have to make him abandon the shortest route and take a detour. He certainly wouldn't be pleased."
"If you don't tell him and I don't tell him, how would he know? After all, he has never once doubted the contents of that book, has he? And not just him—Beatrice in the Forbidden Library is the same. Does 'that person' truly exist?"
"Oh? You care about her?" Echidna chuckled softly. "I merely gave that child a reason to live—a support to fill her hollow soul. Otherwise, if she lost that reason, she would choose to fade away on her own. Is that what you want?"
"If that is her choice," Lillian said, "then yes."
Echidna clearly had not expected Lillian to say such a thing and froze for a moment.
"Living itself is not something that must always take absolute priority," Lillian continued. "If someone believes death is a form of release, then that is fine as well. No one can choose to come into this world—if they cannot even choose when to leave it, then human rights are nothing but a joke."
"Wouldn't that make you sad?" she asked.
"Who? You?" Lillian replied. "If you truly felt sadness, you wouldn't have made her wait hundreds of years for someone who doesn't exist. As for me… perhaps I would feel sad. But if it were her own decision, I wouldn't interfere. In the end, when people talk about 'saving others,' is it really for their sake—or just to satisfy one's own desire to be a hero? It's hard to say. In that case, it's better to let her decide for herself. Of course, if she asked me for help—said something like 'please help me'—then I would help her."
"Tch."
After hearing his words, the way Echidna looked at him changed slightly. She pondered for a while, then nodded.
"Very well, I agree," she said. "If you can pass the second trial, I will alter certain contents of my poor student's book. However, I also have a condition."
"What is it?"
"You must open your memories."
Lillian frowned slightly. "I already told you—the later parts of my memories aren't something I can control. They're protected by some extraordinary—"
"Yes, by some 'extraordinary' power. I know," Echidna said, her eyes shining with excitement. "I've already seen through it. That 'extraordinary' force is not active—it is passive consciousness. I believe its trigger condition is this: when someone attempts to spy on your memories, or harbors malicious intent, it activates its defense. Otherwise, it remains dormant."
"…"
"So I've thought of a way to avoid triggering it. We form a contract. I guarantee that I will not spy on your memories during the trial, nor attempt to observe the process. You, in turn, guarantee that you will completely open your memories and participate in the trial wholeheartedly."
"In this way, the world's binding force will ensure that both of us follow the contract. With no one observing, that 'extraordinary' protection will not activate, and you will be able to face the trial with your complete memories intact."
After explaining, Echidna blinked and gave a playful smile.
"Well? I'm quite clever, aren't I?"