No moment had created so much anxiety for Archimedes as the day he sent Lilith and Anther away to try and convince the boy’s parents how serious his condition was. Since then, Lilith had returned with good news and Archimedes had cooperated closely with the guild in order to attain nothing less than complete approval for his diagnosis and treatment plan.

He had provided exhaustive data for the outsiders to reference, but this had resulted in a several-day delay while the outsiders attempted to verify his findings.

It was hard to be patient, but a recent influx of explorers was keeping Archimedes busy. It wasn’t like Anther was a genius elf child: there were people among the explorers who progressed just as far as he did and faster. A few demons and a beastfolk had actually made it all the way to his third floor: breaking the elf child’s record.

There were clever elves among the explorers as well, but they tended to turn around the moment they set foot on the second floor.

Many logistical problems were currently swamping the small and overpopulated dungeon, so finding a way to make elves comfortable in a mana-less environment was currently low on his list.

He lacked the time, the ideas, and the stamina to constantly change his puzzles, and he had allowed visitors to bypass puzzles they had already solved (so that they wouldn’t give away the answers to observers), but this was a situation where solutions created further problems. Was he to give away free prizes to people who returned after solving a puzzle once, or was he to offer them nothing and make returning to the dungeon pointless? Archimedes found neither acceptable.

The idea he had settled on to solve this conundrum was trade.

Visitors could provide a new food on the first floor in exchange for either a mithril ingot or their choice of an already registered food as their reward.

Visitors on the second floor had to mine the metals they wanted from the walls themselves, spending more time there and allowing Archimedes to harvest more mana and memories from them. The same applied to anyone who hung around foraging.

On the third floor, the reward was the knowledge in the books and bundles of trick spider silk, a material with good strength and mana conductivity. After the first visit, guests could provide a new book or verbally recount a story that the dungeon would transcribe in order to claim another portion of their prize.

Eventually he would have enough books and food and would need to figure out some other arrangement, but that wouldn’t be for a while.

There were still some explorers who wanted to fight the monsters. So far, Archimedes had refused them, but he was considering allowing it for people who had reached the end of his dungeon already. Every defeat would dig into his mana reserves, but maybe it was worth giving his immortal monsters battle experience.

He wanted an arena and teleportation circles leading to it if he was really going to go through with it, though, so it was still on hold.

After one of his busiest days so far, Archimedes watched the crowd filtering out. They were orderly for the most part. One beastfolk man who had failed to get past the first floor swung his pickaxe at the entrance door, only to bounce back with a metallic clang and a pained grunt.

“Fuck, this isn’t mithril! This is mithril-steel!”

A few other explorers nearby chuckled at his expense, including a tall beast woman with a large sack of ore hung over her shoulder.

“Keep at it,” she teased him. “Maybe you can crack it faster than you can solve the puzzles.”

“Dammit,” he grunted, rubbing his sore palms. “Give me a hint at least.”

“And get on the dungeon’s bad side? No thanks!”

Archimedes nodded internally. He hadn’t needed to withdraw prizes from nearly as many explorers as he expected before the rest fell into line. The power of greed was as reliable as always.

Now that the crowd was basically dispersed, however, Archimedes saw someone in a familiar black uniform approaching his entrance.

Finally.

Usually he would have mixed feelings when seeing a guild employee, but he had been eagerly awaiting approval for days now. He hadn’t halted his expansion, but he had never let his mana supply dip below what he would need to treat Anther.

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He was almost eager enough to overlook the oddity of the demon approaching him. Almost. Though his brief peek didn’t reveal anything different between a natural hornless demon and the artificial one he had once created.

“Have you finally come to a verdict?” The dungeon had a sign ready and waiting for when the demon was close enough to read it. “Or do you require yet more data that will take your researchers precious days to verify?”

The demon stopped to read the sign and blinked in apparent confusion. A moment later, he put a smile on his face.

“There seems to be a misunderstanding. My name is Ulbert Nzeft Irenthi: I’m from the Dungeon Research Institute, not the Explorer’s Guild, though they are affiliated.” He tapped a silver badge shaped like a polyhedron pinned to the left side of his collar. “I’ve come to give my greetings.”

It took a moment for the letters on the sign to change. “I see.”

Ulbert smiled apologetically. “I’m sorry to disappoint you. I hope this makes up for it.” He pulled a piece of firm, transparent material out of his pocket. “This is a gift.”

Archimedes attempted to examine the fragment. His excitement built further the more he failed.

“A material which mana doesn’t permeate. Interesting.”

Even as Archimedes wrote the words, he had found a way to probe the material with ether instead and translate the results before consuming it completely.

[New materials added: Etherium]

Ulbert elaborated as the fragment disappeared from between his fingers. “We use it to store liquid mana in pressurized tanks. I’m sure you can imagine other uses as well. It’s called Etherium.”

“I never knew such a thing existed,” Archimedes replied, “yet it seems so simple once you’ve seen it. Thank you.”

Archimedes was certain the Dungeon Research Institute gave a piece of Etherium to every new dungeon they found, but he wasn’t complaining. If only he had less on his plate at the moment, he would’ve wanted to start experimenting with it right away.

“I’m glad you like it,” Ulbert said while glancing at the elf watchman. “I have one more matter to address before I go, but it’s better to handle that inside.”

“I never thought I would invite another Irenthi inside.”

“You must be referring to the junior guild inspector,” Ulbert smiled apologetically. “Cherise is my younger sister by three centuries. I heard that she caused you trouble in her inexperience, and I’m very sorry about that.”

“We have reached an agreement,” Archimedes answered. “And I am slowly recovering.”

The demon held up his empty hands and smiled placatingly, “Well, as you can see, I’m unarmed and incapable of magic, so…”

So there won’t be a repeat of the mess your little sister put me through, Archimedes filled in the unspoken words on his own. Well, he does have an impressive physique thanks to that demon heart, but it isn’t like he can properly compete with a Black Wolf. Mass is insurmountable when competing with brute force.

It was a principle Archimedes had applied with great success as the Dungeon of Behemoths.

Archimedes decided the risks were minimal and opened his doors for the hornless, allowing him into the first floor’s main cavern.

“It’s great to see this in person,” Ulbert mentioned, looking around at the scenery and the artificial sunlight. “One of the DRI’s policies is not to direct any dungeon’s decisions, so it’s always a pleasant surprise to find one who pays attention to aesthetics on their own.”

Archimedes was unused to compliments—let alone those from strangers. The temperature in the dungeon rose, and he changed the topic to allow his embarrassment to subside.

“You said you had a matter to address?”

The dungeon researcher nodded. “Maintaining trust is our foremost goal at the Dungeon Research Institute. Since it’s come to our attention that you can read minds like certain other dungeons can, just like we do for them, I will hang around for as long as you need so that you can read mine. Feel free to take a look at all of our written policies and how they’re actually handled in practice; take a look at other dungeons I’ve visited; examine my personal memories: neither the DRI nor I have anything to hide. I only ask that you keep any sensitive matters you discover on a need-to-know basis.”

At the same time as dungeon greed—a greed that loved obtaining as much as possible as efficiently as possible—threatened to cloud Archimedes’ judgment, warning bells rang in his mind.

“What do you gain by allowing me to do so?”

Ulbert chuckled, “We relieve that suspicion that all mindreading dungeons seem to share. Don’t underestimate the prosperity that the relationship between our races brings us; we have everything to gain by welcoming another dungeon ally.”

Archimedes pondered for a moment, but he found no faults in what the researcher was saying. Between warring with a dungeon and having a dungeon willingly produce resources it knew its allies needed, there was a gulf as wide and obvious as could be.

Of course, this street went both ways. Future dungeons this man visited would know as much about Archimedes as he did.

But so what? Aside from taking inspiration from his creations, what were they going to do? It wasn’t as though they could come over for a visit. And his more precious secrets should be safe: it wasn’t like Ulbert had a dungeon’s analytical ability. He probably didn’t even know he was standing in the middle of a brand new biome right now.

“Understood. Please make yourself comfortable.”

He delved into Ulbert’s mind. Thanks to the absence of demon mana, it was as easy to read as a human’s, with the one caveat that it contained multiple centuries worth of memories.

In the interest of efficiency, the dungeon core opted to save a complete copy of Ulbert’s mind in his memory, in order to parse all the detailed memories out of it later, slowly. With any extra time he had, he planned to search for matters of importance, so that he would have the man himself here to question if necessary.

While Archimedes was hard at work, Ulbert took a leisurely stroll around his first floor, eventually stopping in front of the path to the second floor. Despite the minimal risk, Archimedes didn’t open the door for him.

“While you’re getting your answers, I have a question,” the demon stated.

Archimedes wasn’t thrilled by the distraction, but he had three layers to his core now, and he could spare a little attention. It was only fair.

“What is your question?”

“Are you alright?”