After Sophia had gotten a little bit disillusioned by the first-ever humans she met in this world, she distracted herself with magic. The girl came up with an overpowered combination of the fire and air magic categories. It was so impressive that Fen just had to learn it as well.

"Well, I agreed to teach you, but I don't have the slightest idea how…" Sophia's life as a teacher was going to be a short one. "I know what oxygen is. Okay, to a degree I can work with. It's part of the air or atmosphere. Too little will eventually kill you, but it's easy to feel it if it's only somewhat lower. Too much, on the other hand, hmm? didn't they use oxygen in hospitals? If the concentration of the other gases gets too high, you'll also have a bad time, but oxygen? There was something like oxygen poisoning, wasn't there…? I think divers had that problem, but I think that only applied to pressurized areas, like underwater, right?" She was thinking about how oxygen was used in her old world. "Yeah, hospitals definitely used it when people had trouble breathing for whatever reason… I think I saw athletes using these mask thingies from the hospital as well before… It shouldn't be a problem if I do a demonstration in both ways, right?"

"Uhm…?" Fen had no idea what was going on, but Sophia's incoherent mumbling made him slightly concerned.

"Hey Fenny~, how about a little experiment?"

"D-Do I have a choice…?" He thought her eyes were super scary and that his answer wasn't of importance.

"That depends on whether you want to use my magic or not."

"Fine…" His desire to use more powerful magic was stronger than his fear.

"Great! Okay, let's move to a more open space, then." She guided the wolf to the plain next to the camp and then moved a good bit away from him.

"Why are you retreating?"

"Safety measures."

"Ehh?!" He didn't like the sound of that.

"Don't worry, it won't kill you."

"Hey! Don't you normally say it won't hurt you in this situation?!"

"…" She remained silent.

"Hey!"

"Anyway," Ignoring him, Sophia continued. "As I can't explain what oxygen is, I'll try to show you what it does instead."

"That means?"

"I'm going to decrease the oxygen around you."

"Hey!" He was repeating himself. "That will kill me, won't it?!"

"Relax, I'll only lower it to a point where it affects you but doesn't do any lasting damage."

"Really…?"

"Of course." Ignoring any further protests, Sophia started to decrease the oxygen levels around Fen bit by bit. "Can you feel anything yet?"

"It's getting… a little hard to breathe. A bit like on a high… mountain…?" His voice sounded somewhat ragged.

"Good, a little more, then." She continued to tinker with the air for a while.

"Sophia… haa… I'm getting… dizzy… it feels like… I'm going to… lose consciousness… soon…"

"Okay, that should be enough." Immediately after, the girl slowly let the oxygen return to normal. "Are you alright, Fen?"

"Somehow… That was scary!" He hadn't liked the experience. "It was a bit like suffocating, but… different? You can breathe… but it doesn't work properly. It's not like there wasn't any air, but I could feel like something crucial was missing…"

"Yeah, that something was the oxygen."

"I see… it's still a foreign concept somehow, but I think I'm starting to understand a little." He was getting a grasp on it.

"Great. Okay, I'll increase the oxygen now instead."

"That won't be as… scary, right?"

"Not even close." Reassuring him, she started to raise the concentration. A couple of minutes passed before Sophia asked him about his status. "And?"

"Much more subtle than last time… I can feel something, but I'm not quite sure what it is."

"Okay, let's continue." Going on for a while, the oxygen levels around Fen continued to rise. She wasn't exactly sure how high, but it felt like a good part of the air had become oxygen. "You have to feel it really well now, Fen."

"I do, actually… I feel… great? Breathing has become super easy. My body feels kinda light… It also seems like I have much more power now. Physically speaking."

"Yes, that's oxygen for you. It's the same kind of magic I used together with the fire magic earlier. I just didn't raise the oxygen that high this time. After all, I'm not sure if it's a good idea to breathe in too much of it."

"I see… Okay!" Closing his eyes, Fen concentrated on his surroundings, taking rhythmic breaths to feel the concentrated oxygen in the air better. Sophia let him do so for about 15 minutes.

"Fen, how is it? It's becoming very tiring for me to maintain it…"

"Ah, yes, can you slowly lower it?"

"Okay." Doing as asked, she began to let the oxygen levels go to normal, but it was happening way slower than she had thought.

"Gah… it's super hard!" Fen groaned for some reason.

"Hmm? Oh, are you trying to maintain the level on your own?"

"Yeah, it's way harder than expected, though…"

"Good work!" The two continued like that, Sophia decreasing it while the wolf tried to maintain the oxygen. He eventually succeeded in having it stay at a much higher level than usual, albeit not as high as Sophia managed.

"Okay… I think I'm getting it now… Being at the same level as you is just a matter of training now." He seemed happy about his progress.

"Excellent job. You sure are talented, huh?"

"Somehow, hearing that from you… hurts." The wolf clearly wasn't the prodigy here, at least between those two alone.

----------------

Thanks to the special training being seriously exhausting, the two decided to take it easy afterward until it was time for dinner.

"So you've gone for yet another kow, huh?" She looked at his dinner, just having to comment.

"Naturally. Well, after I saw you playing with one earlier. I got hungry and wanted my own. What about you, Sophia? You sure went wild on this area's vegetables." Looking at her meal, he saw that she had basically thrown together every edible plant that she could find.

"Ahaha… There's no better way of finding out which of these I like or not by tasting every single one in one go. Ah, but save me a bit of this superior being, okay? I want to know how such a ferocious beast tastes." The girl was pointing at the big slab of kow meat Fen was roasting over the fire.

"Eh? It was quite hard to slay, okay? I almost got killed while hunting it." He played along with her joke. "But then, you managed to gather those vicious plants, so you know what I'm talking about, right?"

"Absolutely! I have no idea how I made it out alive…" For them, slaying kows and gathering plants had about the same level of danger.

"…"

"Ahaha…" They had to laugh at themselves.

"Ah, but to be serious again, this kow is seriously delicious because it's way fattier and the meat's softer than the ones we ate before. It tastes like it got to sleep and eat all day because it had no fear of getting predated in this area."

"No wonder. What do humans even eat? Meat doesn't seem like a viable option."

"Maybe even smaller critters? Fish? Probably lot's of plant-type based food?" Fen wasn't sure, either.

The two spent joking and eating together until the sun had set in the evening. Noticing that it became dark, Sophia looked like she wanted to ask something.

"What's up?"

"Hmm… About dark magic… Can I get an introduction to it? It's the last I'm missing after all."

"I'm not sure… I'm going to teach it to you eventually, but is now a good time?" He had his doubts about the timing.

"What do you mean?"

"Well, dark magic… is somehow the… dark side of magic. Curses, soul corrupting, mind manipulation, all such nasty stuff is part of that category. Also, it resonates with the negative feelings of the user, basically powering up when you harbor some sort of negative feelings about your target." Fen gave her an overview of how the magic works.

"And what do you want to convey to me here?"

"We're going to visit a human city tomorrow, right? After today's incident… Sophia with dark magic, getting angry at the city gates… I might get to witness the end of humanity. Again, personally, I don't mind, maybe looking a tiny bit forward to it, to be honest, but…" He came back to the topic after enjoying the idea for a second. "You might not feel the same way."

"Am I really such a… ticking time bomb?"

"Yes." The wolf didn't try to deny it.

"I see… that's… shocking." She thought about the implications for a while. "So, how do I get started on dark magic?" Not too long, though.

"Are you sure about it?"

"Yeah, if I punish them, they most likely earned it some way or another. Also, if I were to run out of control completely, I trust you to stop me, Fen." She made her decision and had faith in her companion.

"I'll try, but I'm not certain I would actually be able to…" The wolf had become to doubt his strength when it came to Sophia.

"Not with force, but I'm sure your words would reach me, stopping me from going berserk."

"You're such a high-maintenance woman."

"That's… not entirely untrue." She wanted to refute his accusation, but she noticed that he was right.

"Well, whatever." He accepted her choice. "Dark magic, huh? Sure, let's give it a try. What could possibly go wrong?"

"I'm ready!"

"Hmm… Sophia, look at your shadow."

"Okay…?" It sounded like an odd request, but she followed suit. She stared at her shadow, which was flickering behind her, thanks to the campfire.

"Try to move your shadow without moving your body."

"Ehh, moving my shadow…? Hmm-" She had no idea how that's supposed to work. "Shadows are… basically created by light. Without light, there are no shadows… ironically, just darkness would be left. Covering the light would… hmm, absorbing the light would work, I guess? Or creating a space so dark no light could penetrate…" Her initial task was forgotten entirely while she became lost in her own world.

"Sophia…?" He had a bad feeling.

"Hrmm… Could I create darkness by myself? I can create light just fine, so? Wasn't there some sort of black in my old world that was so dark that it reflected absolutely nothing, even absorbing light…? So, recreating something like that… Does that even count as dark magic in the first place? You also said the magic's amplified by negative thoughts, right? How about I think about my lovely encounter with those humans while trying it~? Well, let's give it a try and let Fen judge… Darkness… dying everything around me in darkness… absolute darkness…" Her words had become quite dark as well. While she was muttering her thoughts, pitch-black darkness started to ooze out and crawl away from her feet, slowly covering the area around her in black nothingness. It even spread over the campfire, robbing its light that was illuminating the place. The further the blackness reached, the faster it was covering the area in perfect darkness. Soon enough, nothing but Fen and Sophia were left.

"Er…" The wolf had asked her to move her shadows, but the girl turned everything to nothingness instead. He actually had no idea where he was going with the shadow thing. Still, Sophia had taken her own path anyway, an approach he was unable to comprehend.

"So, uhm, does that count as dark magic?" She wasn't sure what kind of magic she had actually done.

"Uhh…" While profoundly sweating all over his body, Fen was still trying to wrap his head around the situation. He was unable to do so, though.