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“Why the hell are you wearing a sweater?”
It was a fair question in Kurogane’s mind. They had stopped off in Clow again, this time landing in the middle of summer. The kids were fine in their regular attire. Kurogane himself had not even looked at his cloak since he arrived and was half-tempted to tell Mokona to spit him out a pair of shorts.
Fai, however, had boots, long pants, and a sweatshirt of all things he’d pulled on over his shirt. It should have been considered a minor miracle he hadn’t passed out from heat exhaustion already. Fai seemed to be of a different opinion, grinning cluelessly between bites. “Because I’m cold.”
“There is no way in the multitudes of hell you’re cold,” Kurogane argued. Fai was skinny, but no amount of fat or lack thereof justified needing a sweater in this kind of weather.
“I’m always cold,” Fai countered before continuing thoughtfully, “Though it has been worse lately. I must be getting old.”
“Fai-san,” Sakura cut in, curiosity just barely winning over the concerned pinch in her brow, “Is it possible you’re anemic?”
“Nimyk?”
Sakura and Syaoran shared a look. “No, anemic,” Syaoran corrected, and Fai only looked confused. “Having anemia?” No recognition of the word crossed Fai’s face. “Not having enough iron in your blood?”
Fai laughed brightly at that, as if he finally got the joke, though there was none to be had. “Oh, Syaoran, everyone knows blood and iron don’t mix!”
“Yes, it does,” Syaoran insisted, going from concerned to mild fretting. “The cells of your blood literally need iron to exist. You have to have iron.”
“That can’t be right,” Fai said, though now he didn’t sound so certain. “Iron’s a poison; that’s why sword wounds are so deadly. You can’t even handle it without gloves unless you’re looking to get burned. I don’t want to think about what would happen if you actually ate some.”
Syaoran’s face went from worried to alarmed, and he wasn’t the only one. “What.”
“What?” Fai parroted, apparently not understanding the confusion.
“Fai-san, are you..?” Syaoran started, flabbergasted, before changing his mind. “We should take you to see Yukito-san.”
“Ok?” Fai agreed uncertainly, and they all abandoned the rest of lunch to find out just what was going on here.
“This is extraordinary,” Yukito murmured once his magic had read all he could from Fai’s systems. “Fai-san, do you feel ill after eating certain foods like spinach or beef?”
“Yes,” Fai confirmed tentatively. “That didn’t start until I left Ceres, though.”
“And you say your people consider iron to be a poison, and that even direct contact with the skin can cause injuries?”
“Doesn’t that happen to everyone?”
“No,” Yukito confirmed gently, “But most people have iron in the cells of their body. It is especially essential in blood. Without it, the cells can’t carry oxygen to the rest of the body, which causes the affected systems to weaken and eventually die. You, however, seem to have ruthenium instead.”
Fai nodded, “Right, that’s why it’s a common soil additive. Both of the worlds I grew up in had mines and refineries dedicated to it. It can also be produced alchemically from uranium or plutonium if necessary, but mining was always preferred because the transmutation process can cause illnesses to the magicians performing it.”
“Well,” Yukito explained, “The same way your people need ruthenium, people from worlds like ours need iron. I assume you use it in soil because it helps prevent deficiency-related diseases?”
“That’s right, anrosia,” Fai clarified, before understanding dawned on him in the space of a blink. “Wait, I’m anrosic?”
“That’s right. Ruthenium is a rare metal, at least here on Clow. We don’t even have enough of it to have studied if it is toxic to our systems in its elemental form or not, much less have it naturally in our food. I imagine it’s similar on most of the worlds you’ve visited, and so you’ve developed a nutritional deficiency over time.”
“And that’s why I’ve been cold?”
“That’s why you’ve been cold. You may have also been feeling tired or weak, or have had headaches or a lack of appetite.”
“Wait a minute,” Kurogane cut in. “If he can’t have iron, then how was he drinking my blood before?”
“That was a metabolic change brought on by the vampirism,” Yukito explained. “It actually created a secondary system that would allow the blood to be processed. Fai-san wasn’t able to use the iron nutritionally, but it prevented it from acting as a toxin in his system. I imagine since then, you’ve been able to tolerate iron rich foods better?” Yukito asked, addressing Fai, to which Fai nodded. “Part of it is still active, so I don’t believe you’ll be poisoned by ingesting iron anymore, though it probably won’t correct the contact dermatitis or being poisoned by having it introduced to your body in other ways.”
“So we just have to find some ruthenium?” Syaoran asked.
“Yes, though it is relatively rare.”
Fai shrugged. “We always found and separated it from platinum metals.”
“What about the other crap you used to make it from?” Kurogane asked as Sakura stepped out.
“Those materials are radioactive. That’s probably why transmuting them made people sick,” Syaoran explained. “Since they’re dangerous, we won’t have an easy time finding them, either. Depending on the world, we might get arrested for trying.”
“Well, that won’t help,” Fai muttered more to himself than anyone else. “But maybe if we had some thorium — ”
“Thorium?”
“To make uranium from.”
“It might be easier to try nucleus combination alchemy than fission-based,” Syaoran suggested. “The library has a periodic table. We could see if there are two relatively common elements we could combine to create the proper nucleus for ruthenium and balance out the electrons from there. You wouldn’t happen to know which isotope you used in your world?”
“Does it matter?”
“We wouldn’t want to hurt you by introducing an incompatible isotope to your system, though it’ll probably be alright so long as we don’t produce a radioactive one. There might be books in the library — ”
“Does this have ruthenium?” Sakura asked as she reentered the room, passing a bracelet to Fai, who reached through it with a touch of magic.
Fai smiled. “It does, but are you sure, Sakura-chan? Extracting it will probably destroy the bracelet, though I could probably make a smaller one from the leftover metal.”
Sakura nodded emphatically. “I want you to have it! Your health is worth more than a bit of jewelry.”
“Thank you,” Fai replied as he pushed the bracelet on his wrist. “We should probably still check the library. It’s been a while since I’ve done an elemental separation spell and I wouldn’t want to waste Sakura-chan’s gift.”
Hours later, when they had retired to their rooms, Fai paused to fiddle with the bracelet after adding a little more detail to some of his notes. Between Yukito, Syaoran, and himself, they’d managed to pull together enough knowledge that Fai had been able to reconstruct the basic theory. All that had been left was a little fine-tuning to account for any impurities in the ores. Now, though, he’d taken the spell as far as it could go without applying actual practice. Instead, he took a moment to admire the craftsmanship of Sakura’s gift. “I always wondered why other worlds had so much less magic in them,” he commented absently. “At least now I understand why.”
“The iron?” Kurogane prompted.
“Mm-hmm,” Fai hummed with a nod. “Iron and magic aren’t really compatible. We only used it for restraints and defensive tools like shields so they’d be resistant to spells. Knowing you’ve got so much of it in you…” Fai shrugged. “It all makes sense now.”
“People had a lot more magic on your world?”
Fai nodded again. “My brother and I were still considered extremely strong, but it was rare to even encounter small children whose magic was around Syaoran-kun’s or Sakura-chan’s level. Even children in the womb had more magic than you do.” If Kurogane was offended by that, he didn’t say anything, and Fai continued after a few moments. “Fei Wong made sure to destroy Ceres. Even if my second curse hadn’t activated, I don’t doubt that he had some influence over Ashura-ou’s madness. Probably the Valerian king’s, too. He probably saw such magically gifted worlds as a threat and destroyed them before their people could band together against him.” Fai paused, gazing out the window. “I might be the only person left in all of existence whose blood contains ruthenium instead of iron.”
Kurogane reached over and ruffled Fai’s hair. “That's just one more reason for me to keep you alive longer.”
Fai’s answering smile was small, but fond. “I should probably take us to Valeria next. There might be some salvageable books there about biology and ruthenium. We’ll probably need them eventually.”
“Will you be okay?”
“Not if I freeze to death,” Fai replied lightly without answering Kurogane’s real question as he finally pulled the bracelet off his arm. It glowed briefly between his two hands, and when the spell was complete, there were two balls of metal in its place. Fai set the smaller one aside and began applying more magic to work the remainder, stretching and forming it until it became a bracelet again, identical to the original except that it was now thinner and daintier than its original form. He placed that back on his wrist and picked up the ruthenium sphere for study. “Still, we’re not going to be anywhere long enough to farm properly, so I’ll need a bit more study to turn this into a form my body will accept as a supplement. Platinums aren’t the easiest kind of metal to acquire; it’ll be best to make sure none of this goes to waste.” Kurogane didn’t say anything to that, and Fai knew he wouldn’t — not until Fai gave him a real answer — and so he turned enough to meet Kurogane’s eyes. “I’ll be fine,” he decided, and though his body felt cold, his heart was warm. “My family will be with me, so I’ll be fine.”