Felix climbed in silence for a while. He was starting to get a little bit weak from not having any food, so he stopped often by carving out small nooks on the side of the mineshaft to rest. During one such rest, he asked Arboro,

"Don't you know any spells that would make this faster?" He grumbled.

"Of course I do, Earth is of Yin as well, so even though it isn't my element I know a few low level spells of it. But, even though you're a mid-grade mage now, I don't think you would save any time constructing them in this vertical shaft. And right now you need to reach the surface quickly." She mused.

And so, with a sigh of annoyance, Felix continued to climb. Luckily, he was strong from his orchard work through his life, so he was able to make good progress, and he reached the underground river after only two days of climbing. He was incredibly thirsty, so he drank his fill and then laid on the ground nearby the river to rest, his stomach growling.

"I'm so hungry. Arboro, don't you know any spells to make food?" He asked hopefully.

"No child, no such spell exists. Well, at least not directly. There are wood spells that could, for example, cause a plant to grow quickly, and then to create fruit quickly, but, that would require you to have seeds, and light, and wood element to construct the spells in your spell space." she said, and shrugged.

"I do have seeds actually. But yeah, there's no wood element down here, and no light, and I'm not a wood mage anyway." Felix sighed.

"About that... actually, you should be a wood mage now." Arboro said.

"What are you talking about Arboro? You know I'm an earth and dark mage." Felix said, putting his hand on his head.

"Well, you remember how you dark attribute was strengthened when I joined with your soul? That wasn't because I'm the grand spirit of the dark element, it was because I have a darkness affinity. If you go to an area that actually has wood element in it, your core will probably strengthen itself again and you'll gain wood as a sub-element." Arboro said.

"Huh? I mean that's great if it's true, but if that's the case, then why did I also gain earth element after you fused with me?" Felix asked, sitting up straight.

"Because you have earth as your main element. The darkness can't supplant earth as your main element, it can only sit right below it in strength, at best. So in order to accommodate my dark magic, it had no choice but to boost your earth affinity first. Normally the dark element wouldn't go through so much effort for a mage, but because it needed you to save me, the darkness buffed you so you could withstand my might." Arboro explained.

Felix stood up and began to slowly climb again, carving out an upward slope like he had originally planned to, but now with renewed vigor from his expectations of picking up a third element. He continued to talk to Arboro as he worked.

"So why don't dark mages do this all the time? Even if they didn't get special treatment like I got from the darkness, they could buff their affinity by attaching a new lesser spirit to their soul, right?" Felix asked.

"Hardly, child. It worked in your case because you didn't have a Yin spirit attached to your soul in the first place. Normally, your affinity is attached to your spirit. Your Yang spirit adapted, and the affinity of two spirits was contained in your one, but normally, splitting your soul in two halves your power, halves your affinities. So you would be trading away half of your soul and your main affinities for at best 2 sub-affinities. Almost definitely not worth it, even if you don't consider the risks associated with splitting your soul, like potentially damaging it." Arboro explained.

"How are elemental affinities determined?" Felix asked.

"They're assigned at birth. Your grade is inherited from your parents, but your affinity is determined by the elements. I suppose the earth and the dark wanted you." Arboro said, shrugging.

"So... do the elements think? Are they sentient?" Felix asked.

"They have a will, but I wouldn't go so far as to say they think. They have instincts for sure though. When the darkness helped you by giving you water back in the cave, for example, it was acting on instinct that you were my corporeal vessel, so whatever you needed was in the best interest of the dark element, because I am the grand spirit of darkness." Arboro explained.

Felix took a moment to move a large rock that blocked his path, and he continued to slowly carve his way upwards.

"I was curious about that. How did the darkness create water? Normally that's, you know, a water element thing." Felix asked.

"Water and dark are both of Yin. It isn't easy, and there is a cost, but the Yin elements can all be converted into each other. You should only do it if you have dire need of an element though, the conversion rate is not good at all, it's something ridiculous like 1 to 10000." Arboro explained.

The author's narrative has been misappropriated; report any instances of this story on Amazon.

This surprised Felix. Elements could be converted into other elements? He had never heard of such a thing.

"How is that possible? I've never heard of anyone converting the elements." He asked.

"Like I said, it's because they're both of Yin. All you would have to do is to condense a Yin element back in to pure Yin, and then you can turn it in to whatever you want." Arboro explained patiently.

"Wait wait wait." Felix said, shocked. "You can create pure Yin? Is it like an element? What are it's uses?"

Arboro looked surprised, and thought about it for a bit. "Well, I never actually considered it, because pure Yin is basically non-existent in the world. There are no "Yin affinity" mages, for example, nor a Yin race, and it would be difficult to gather enough Yin element to construct a spell framework, and that's besides the fact that even if you did go through all that effort, you would have no one to learn from, since no one else has ever done such a thing, to my knowledge. But yes, I suppose you could use it like any of the 8 elements." Arboro theorized.

Felix made a mental note to examine the Yin path when he found the time to. It might give him unique advantages.

"I've been wondering. Can you cast spells in your current state, Arboro?" He asked her.

"No. I could when I was a detached spirit, but now that I've become your lesser Yin spirit, bound to you as a vessel, the only way I could possibly cast spells is through using you as a medium, and at best I can only do a low-grade spell or two, with great effort, and if you resist at all, it will fail. The only way I could use magic at my full strength is if you gave me control of your body by promoting me to be the primary aspect of your soul." Arboro explained.

Felix shivered at the thought. Giving up his soul to Arboro could be considered as an absolute last resort, he supposed, but otherwise he would never do such a thing as give up his very core to another.

"I thought not." Arboro said, seeing his reaction. "Still, you might consider forming a pact with me where I can take control in the event that you're in mortal danger or incapacitated. You should consider it." She said, rather seriously.

Felix nodded, but refrained for the time being. He continued to dig upwards.

"I've been thinking about this. What will I do when get back to the surface? If anyone finds out about you, I'll be toast..." Felix muttered.

"Well, explain to me what happened before you met me." Arboro said.

Felix explained the events leading up to him meeting Arboro. He told her about being conscripted, about the dark mage's blockade, and about the demon light mage who chased him deep into the earth, and how he fell into the underground river, and barely survived.

Arboro smirked. "Isn't it obvious, child? The military used you as bait." She said, laughing.

"Huh? How do you figure?" Felix asked, dumbstruck.

"Come on now. Do you think the military would gave you a bunch of salted meat and rations out of the goodness of their hearts because they want you to live? Heavens no! They left you out there, isolated and alone on the flanks on purpose, and gave you all of those extra supplies so you could survive when you inevitably got attacked and ran." Arboro explained, rolling her eyes.

"But... why would they do that?!?" He yelled angrily.

"Well, you said there was a water mage nearby watching you, right? You said he wasn't really paying attention to you, but that's just what he wanted you to think. I would be willing to bet you my left wing that he was paying extremely close attention to you at all times, and that he watched every second of your interactions with that demon light mage up to the point that you fell into the chasm, and he reported every last detail to his boss, to use the information in the upcoming battle." She said, still smirking.

Felix was extremely angry. He thought that his unit leader was just being nice, but actually he was just using him as bait! He stomped the floor in anger, and stopped and sat down for a moment to meditate in order to calm himself.

"Okay, let's suppose you're right. Then there shouldn't actually be any issue with me going back to the Aurul Kingdom then, right?" Felix asked.

"There shouldn't be. I doubt they will admit they used you as bait, but if you explain you were running from a demon, which they will be able to collaborate with their own information from the water mage, they'll just pretend to be angry and give you a slap on the wrist, probably." She said.

"But what if they soul search me and find you? Or they find out about my new affinities?" He asked.

Arboro laughed. "You overestimate your value child. It's nowhere near worth the effort to soul search you over something so trivial, and even if they did, they wouldn't find anything unusual. If they DID bother soul searching you, it would be a very basic one, and I would just look like the other half of your soul. If they scoured your memories, all you would have to do is to focus on your memories of the fight with the light mage, and that would satisfy them." She said.

Felix thought about it for a bit and he supposed that made sense. He nodded and continued to dig. He dug, and he dug, and occasionally he returned to the river for water. Eventually, after a week of digging upwards, he sensed the surface through his examinations of the earth element, and determined he was behind Fort Basil, on the side of the Aurul Kingdom. That was fortunate at least. About a minute after he sensed the surface, he heard a voice in his head.

"Halt earth mage! Digging around here is forbidden! State your name and why you are here, or you will be attacked!" the voice said.

"Uh, my name is Felix, and I'm with the environmental engineering team. I got split up from my unit about a week and a half ago after I got chased by a demon light mage." Felix explained. He then remembered he had his chevron pin and his identification token in his pouch with his wheat seeds, and took them out, holding them up in case whoever was speaking to him could somehow see him.

The voice was silent for a bit, and it felt like Felix was being stared at. Finally, it said "Understood. Sit tight, and we'll send an earth mage to extract you."

Felix sat down on the slope he made, and after a few minutes, he felt another earth mage heading in his direction. Eventually the earth mage reached his position, nodded at him, and grabbed his hand. He waved his hand towards the slope and the entire slope collapsed, and he escorted Felix back to the surface outside of Fort Basil. After only a couple of minutes of moving through the earth, he returned to the surface.