Author Notes: Some info to clear things up. I'm going to tweak how Binding Vows work a little. After looking at more JJK lore, some binding vows are just unfair as heck. Like Nanami's is just a win-win for him. Even if he breaks the clause of his Binding Vow, he just loses what was gained, and in his case, he goes back to normal, like that's just not fair.
Also, on an unrelated note, I'm nearing my final exams, so chapters might not come out as fast. Please help, I am dying.
Anyway, hope you enjoy the chapter!
/ --- /
Ren
Ren had been staring at a blank piece of paper for around twenty minutes. This was not because he didn't know what he wanted to make, he knew that much.
It was because knowing what he wanted and knowing how to get there were two different problems, and the second one was giving him significant trouble.
He picked up the brush finally and wrote at the top of the page: [Cursed Tools: Armbands.]
The question that still remained was how.
That was the problem in its entirety. He had decided on armbands rather than pins. They were more practical for physical work, harder to lose during a delivery, and visible enough to function as a brand identifier for the Shadow Courier.
He needed the armbands to give their wearers a meaningful boost in speed, endurance, and overall physical stats.
It wasn't a subtle improvement. He needed something that would actually close the gap between his employees' natural physical ceiling and what his clients expected from the Shadow Courier name.
That was a specific effect with specific parameters, and getting it into a physical object was tricky.
His first option was gradually imbuing the objects with Cursed Energy.
Technically, this was the simplest and easiest way to do it. You took an object, you pushed CE into it consistently over time, and eventually it became a cursed tool through accumulated saturation.
He had heard of many tools that were worked roughly this way. The problem was that gradual imbuing produced a tool that was essentially CE-saturated.
It was useful for interacting with curses, but it didn't have any defined properties beyond that. If he did this, his employees would have armbands that could theoretically give them CE as long as they wore them. But it wouldn't last long and wouldn't give them the effects he wanted.
He needed specific effects on the wearer's physical capability. Gradual imbuing couldn't give him that without something else on top of it.
Another option was the ritual for making Cursed Tools with properties.
The ritual was an option was a clearer one, but it was also where he hit a wall. Proper Cursed Tool imbuing rituals were specialized knowledge.
He knew they existed. He knew his father had explained them at some point. He also knew that he had been sixteen and significantly more interested in refining his Ten Shadows than in the theoretical framework of tool production, and that he had retained none of the info his father had told him.
He put the brush down and pressed the heels of his hands against his eyes.
'I should have listened more. I'm an idiot…' he grumbled, which was not a new thought but felt more pointed than usual given the current situation.
So that left one final option he could fall back on. One that he was really hesitant to use.
A Binding Vow.
A Binding Vow used during the imbuing process would allow him to define the tool's properties without many hurdles.
The problem was complexity. Binding vows were not casual arrangements. The more specific and powerful the vow, or who you make the vow with, the greater the cost and the greater the risk of getting something wrong.
That wasn't even accounting for how a Binding Vow would work in Teyvat. This was a world without Cursed Energy, so there was no way of knowing how the world would respond.
Heck, it might not even work at all.
Making a Binding Vow with yourself wasn't an uncommon thing in sorcery, but using it with other people had significant risks.
Ren had no knowledge of anyone using Binding Vows to make Cursed Tools, so he had to go out on a limb and theorize what the consequences of breaking this kind of vow were.
Breaking a vow with yourself would make you lose the abilities gained, while also making it impossible to do the same vow ever again.
But breaking one with another person was never documented, as no one ever dared to try.
He would need to think it through extremely carefully before attempting it, and he would almost certainly need Yanfei's help to structure the vow, as this was basically another contract as far as she was concerned.
He technically had one more option. But he completely crossed it out from his mind.
Using a sorcerer's remains, or in Teyvat's case, presumably a Vision wielder's remains, as the base material for a cursed tool produced powerful and durable results.
It was pretty straightforward. But he also understood that it was inhumane and grotesque in a way that sat poorly with him regardless of how he tried to frame it, and practically speaking, would require him to source bodies, which was an entire separate problem that he had zero interest in solving.
'Technically, I could just grave rob Huang's remains—No, bad Ren.' He thought, shaking his head.
The binding vow approach was the way to go.
That meant setting up another meeting with Yanfei to work through the vow structure, which he was not particularly looking forward to explaining, but which was unavoidable.
Now with the method out of the way, the last piece of the puzzle remained.
'What material do I use?' He scrunched up his face and tapped the pen on his head.
Normal iron was the obvious answer. It was cheap and easy to work with. The only problem was durability.
These tools were going to be imbued with CE and locked with a binding vow, worn daily by people doing physical courier work across Liyue Harbor and, eventually, farther.
Normal iron under those conditions would degrade faster than he wanted, and replacing them regularly meant re-imbuing them with CE regularly, which was a big hassle.
'I could technically make another vow to make the armbands resupply CE itself… But I would need to give up something of equal value, so probably not that.'
On the other hand, white iron was a better material. Significantly more durable, and would handle the CE saturation better over time.
But it was also freaking expensive, so sourcing a lot of white iron from established suppliers would hit his margins harder than Shenhe's punches.
The regulations around independent mining in Liyue meant he couldn't just go find some himself without a substantial amount of bureaucratic effort.
So white iron was a last resort.
"What a pain in the ass…"
There might be something else. Something Liyue-specific that he didn't know about yet, some local material that had the durability he needed without the cost.
He hadn't been in Teyvat long enough to have a comprehensive understanding of what was actually available in the region's geology, which meant the best option right now was research.
The library had a geology section (obviously). So that's where he was going to start.
/ — /
He was not far from the library when he turned a corner and nearly walked directly into someone.
Thankfully, he stepped back just in time and was about to apologize, until he heard the voice, and the apology died immediately.
"Ren~! What a coincidence!" Hu Tao was standing in front of him with her typical loud demeanor. She wore her typical attire, with her signature hat to boot.
Ren recovered from the surprise quickly, "Director Hu. I didn't see you there."
"Nobody ever does," she said cheerfully, which didn't entirely make sense but felt accurate regardless.
He noticed then that she wasn't alone. Standing slightly behind her and to the left was a tall man in dark formal attire.
"Ren, it is good to see you," Zhongli said, with a small nod.
"Mr. Zhongli? It's been a while since I've seen you."
Zhongli was Hu Tao's assistant, and he had gotten acquainted with him after a few interactions in the past. The man was easy to approach and was generally just a friendly guy.
It certainly helped equalize Hu Tao's energy, at least.
The first month in Liyue, Ren would have already run off to another nation just from Hu Tao's pestering if it weren't for Zhongli.
That may seem extreme to some, but Hu Tao was a chaotic force of nature who was stronger than him back then. She also had weird energy, so one could imagine his reaction to a person like her after just getting isekai'd.
"We haven't run into each other in a while," Ren said, looking back to Hu Tao. "Actually, I haven't seen you around the harbor at all lately."
Hu Tao tilted her head with a small smirk. "Oh? Have you been looking for me?"
"No."
The speed of the answer made her laugh out loud, which surprised a few passersby and gained some weird looks.
She composed herself quickly, waving a hand. "I've been busy! Business has been absolutely booming."
Hu Tao straightened her nonexistent tie with a smug expression. "New deals for coffins and committal services across three districts, internment arrangements that practically signed themselves, and—" she paused for effect, "—a major new arrangement with Mondstadt!"
'Ok, that's actually very impressive…'
Ren couldn't help but compliment her. "Mondstadt? That must have been a huge hit for you."
"Isn't it?" She looked extremely pleased with herself.
He took a moment to reevaluate his perception of Hu Tao. Her presence had a way of making people forget that, behind the poetry about death and the highly questionable business development strategies, she was genuinely exceptional at what she did.
Under her directorship, the Wangsheng Funeral Parlor had thrived more than almost any comparable institution in Liyue. The Mondstadt deal alone would have taken most business owners years to negotiate.
"That's impressive. Congratulations." As a fellow business owner, he had to respect her success.
She basked in this without any pretense of modesty. "Thank you, thank you. I worked very hard, and it shows." She tilted her head. "Now. How about you? Last I heard, the Shadow Courier was doing quite well for himself."
"Can't complain," Ren said. "Things have been good. Good enough that I'm actually in the process of taking on employees for the first time."
"Oh?" Hu Tao's eyebrows went up and wiggled around in a weird way.
"That's quite impressive," Zhongli said, "When you first arrived in Liyue, you were operating entirely alone. To have built something stable enough to expand in this time speaks well of you."
Ren rubbed the back of his neck, a bit flustered at the praise. "It's certainly been a process… Speaking of which, I should get going. I need specific materials to make equipment for my new employees, and I'm not sure where to start. So I'm heading to the library to look into local ores."
He hadn't planned to mention that specific detail. It came out naturally in the flow of the conversation.
Hu Tao's expression immediately changed into one of delight, and Ren couldn't help but feel a chill up his spine.
She turned to Zhongli and attempted to put her arm around his shoulder, but ended up with it around the upper part of his arm due to the height difference, which she appeared not to notice.
"Zhongli~ You know about ores, don't you?"
"I have some familiarity with Liyue's geological resources, yes," Zhongli said, which Ren would later reflect was possibly the most understated sentence he had ever heard.
"Perfect!" Hu Tao turned back to Ren with the energy of someone closing a deal. "He's your man. Knows more about rocks and stones than anyone in Liyue, I'd bet on it."
She released Zhongli's arm, or the portion of it she had been holding, and straightened her hat.
"Unfortunately, I have a client meeting I simply cannot miss." She whistled and turned to leave. "You two have fun! Don't get into too much trouble." This was directed specifically at Ren, which he found slightly unfair.
Then she was gone, instantly absorbed into the crowd.
Ren stared in the direction Hu Tao had disappeared with a mix of irritation and confusion.
Then he looked at Zhongli.
Zhongli looked back at him with an expression that suggested this was a completely normal sequence of events.
"I apologize for the abruptness," he said.
"Don't worry about it," Ren said, still processing slightly. "Not seeing her for a while made me forget she does that… Does she do that often?"
"With some regularity."
Ren sighed and looked at Zhongli with an apologetic expression. "It's alright, I don't want to take up your time."
"You would not be," Zhongli said simply. "I find the subject interesting, and if my knowledge is of use to you, I am glad to share it. Consider it help from a friend."
Ren looked at him for a moment, trying to see if he was just being polite. Then smiled when he saw his small smile.
He didn't have a good reason to say no.
"Alright then. Thank you, Mr. Zhongli. I appreciate it."
/ — /
It took a while of walking before Ren realized they were heading away from the library.
"I thought we were going to look at references."
"A library would tell you what is documented," Zhongli said, still walking forward. "I can tell you what is useful. The distinction matters when you have a specific problem… Unless you would prefer the library?"
Ren considered this for a moment before shaking his head. "No, that's fair. Lead the way."
Zhongli nodded and continued walking.
They moved through the harbor district toward the main gate, the midday crowd thinning as they got further from the commercial center.
"I must apologize once again," Zhongli said, after a moment. "For the Director's approach to the situation. She tends to move quickly without thinking about her impact on others."
"Don't worry about it. She's done considerably… stranger things to me." He shivered. "There was an incident with a commemorative funeral rite in my third week in Liyue that I'm still not entirely sure I consented to."
Zhongli's expression carried a faint quality that might have been amusement. "I am familiar with the Director's methods."
"Of course, you are her assistant after all." Ren laughed. "Sorry for asking again, but are you actually alright with this? She volunteered you without really asking."
"She rarely asks," Zhongli said. "But rest assured, she would not have offered my services if she knew I was uncomfortable. And I would not have agreed if I had not meant it."
That was enough for Ren to stop asking. Zhongli was the type of person who was straightforward and honest. It was a respectable quality in a person, but slightly rare nowadays.
He found himself, not for the first time, wondering how exactly Hu Tao had convinced someone like this to stay on as her assistant.
Zhongli was composed, knowledgeable, and very competent. He seemed like someone who could have done almost anything and had chosen this, which raised questions Ren didn't know how to ask politely.
He decided not to ask them at all and focused on the road ahead.
They passed through Liyue's main gate, and the sounds of the city fell behind them.
"What kind of equipment are you making?" Zhongli asked, after a while.
"Armbands."
Zhongli looked at him, mildly perplexed. "You require metals for… Armbands?"
"Yep," Ren confirmed, rubbing the back of his head sheepishly as he realized how absurd it sounded. "I can't explain more than that. Business reasons and such, you know how it goes."
"Understood." He didn't push further, which Ren appreciated. "May I ask why standard iron won't serve the purpose?"
"Durability. I need something that holds up under conditions I can't fully describe without getting into the confidential part. Normal iron degrades faster than I need these to last."
Zhongli was quiet for a moment, walking and thinking. The path outside the gate curved along the edge of the cliffside, the harbor visible far below between the rocks.
"Cor Lapis," Zhongli said.
"What's that?"
"Cor Lapis forms in Liyue's rocky terrain through mineral concentration, developing a density that makes it resistant to impact and degradation in ways most ores aren't." He explained.
"It also possesses properties under sustained pressure that make it particularly suitable for items meant to be worn and used continuously."
"That definitely fits what I'm looking for. But how rare is it?" Ren asked, then added in a quieter tone. "Is it expensive?"
"Less rare than most people assume," Zhongli said with a chuckle. "It appears throughout Liyue's rocky terrain. Most people simply don't know what they're looking at when they see it."
He hummed before continuing. "Buying them normally is quite expensive. But there are no laws about harvesting Cor Lapis yourself. I know several locations where deposits of useful size can be found."
"...Seriously?"
"Yes."
"And you'd be willing to—I mean, I can compensate you for your time, this has already been—"
"No compensation is necessary," Zhongli said. His tone never changed, but somehow conveyed a sense of finality. "As I said before, consider it help from a friend."
"…Thank you."
"Of course." Zhongli inclined his head. "The largest deposits I'm aware of are on the cliffs of Nantianmen. The stone—"
"I'm sorry, what?" Ren cut him off with a shocked look. "It's all the way at Nantianmen?!"
"Yes."
"That's really far."
"Several hours on foot, yes," Zhongli said, only for his own eyes to widen as he realized his blunder. "We should have prepared provisions."
Ren rubbed the back of his neck. "About that… I have another way to get there. Takes about an hour. Are you afraid of heights?"
Zhongli raised an eyebrow slightly. "No."
"Good." Ren scanned the area once more, then turned toward the open space at the edge of the path, away from the cliffside. "Also, please don't be scared of this. My summons are harmless."
He reached into his shadow and summoned Nue.
The shikigami materialized from the darkness. Nue settled onto the ground, shaking its head as it adjusted to its surroundings.
Ren nervously turned to Zhongli.
Most people, when they first encountered Nue, had some version of the same reaction: Fear or hostility. Even people who knew about the shikigami in advance tended to need a moment.
Zhongli stepped forward.
He examined Nue with an interested glint in his eyes. His eyes moved across the shikigami, moving carefully across its feathers.
He asked, without looking away from Nue, "What a fascinating creature. It is only now that I have realized that I've never seen these summons of yours. Its energy is one I am unfamiliar with."
Ren blinked. "He's a shikigami. Long story short, it's a hereditary technique from my family."
Zhongli nodded slowly, still studying Nue. "Fascinating. Will we be riding it?"
"That's the idea."
Zhongli looked back at Nue and made a small sound of approval. Then he moved to climb up with zero hesitation.
Ren climbed up after Zhongli and Nue rose smoothly into the open sky, the harbor dropping away beneath them.