AN: It's my birthday on Monday. I'm turning 28. So I got this chapter out of the way. It's not my favorite, but it's acceptable, and this is more about getting stuff out regularly than perfecting it.

Anyways, enjoy chapter threeeeee.

When I finally came out of my exhaustion-induced slumber, it didn't turn out to be a short nap. In fact, I'm fairly certain that hunger was the only thing that prevented me from sleeping halfway through the night. As I groggily sat up, my nose informed me that there was some sort of acceptable food on the other side of the bedroom door somewhere. My stomach added a sense of urgency to the demand, but my bladder played a trump card.

Food was my next priority, though, so I let my nose lead me into the living room. I fully expected to have to go out and get my own food, as I hadn't brought any with me, and hadn't anticipated sleeping until early evening.

"Hey, Daniel. Feeling better?" Matthew was eating casually on the couch, feet propped up on the coffee table.

I grunted. "Somewhat. Sore. Hungry."

He chuckled, "Mother insisted on sending us about five pounds of cooked pasta to celebrate me having a roommate. It's got chicken and onions in it. I told her she didn't have to worry about it, but she wouldn't have it. And of course, she cooked enough for the Auror department."

"Oh thank fuck." I muttered in response as I tried not to rip the door off of the refrigerator. I saw the truly enormous pot on the bottom shelf, summoned a large bowl, and then promptly filled it. As I made my way to the couch, I absentmindedly summoned a fork from the kitchen.

"Eating it cold?"

"Don't care. Hungry."

Matthew snorted. "Magical exhaustion?"

"Yeah. Someone forgot to transfigure inanimate to animate correctly." Matthew coughed loudly. "You all right there?"

Matthew muttered something that sounded a bit like "Bugger off."

I waved him off, "You ended up proving my point."

"How so?"

I raised an eyebrow. "You nearly burned down the damn house."

"The dragon would not have burnt the house down." He countered, "It was far too small for that."

I rolled my eyes "It wasn't for lack of trying."

Matthew didn't immediately have a response, and I was far more concerned with the food in front of me to press the issue further. For the first time since I'd arrived that morning, I was able to look around the room. It was fairly standard, with the one large couch, two small recliners with small tables next to them, and a large lamp magically stuck to the far wall. The coffee table was fully repaired from being used as a literal fire shield earlier in the day. The memory made me actually snort, which Matthew ignored.

"How's the mastery in Arithmancy going?"

I shrugged. "It's slow work. I have a premise to work with, but being able to actually manage it will be difficult as hell, not to mention dangerous."

"Dangerous?" Matthew looked incredulous for a moment, "Wait, are you spell-crafting?"

I shook my head, "Not quite. I'm more doing a comparison between similar spells and magical creatures that produce a similar effect."

His brow furrowed, "The only thing I can think of is invisibility, but that wouldn't be dangerous, would it?"

"I don't think so." I cleared my throat. I hadn't planned on sharing this with anyone until I'd completed it. "I'm working on magical fire."

Matthew's eyes widened. "Dragons!" Then, he started laughing.

"Shut up."

His laughter continued, "Was today an experiment, then?"

"Fuck off." His only response was a decidedly unrepentant snort. "In fact, you can fuck all the way off."

"Is there even another alternative? Can you fuck half off?"

"Probably. People are indecisive, you know."

He laughed again, then coughed, and proceeded to laugh harder. He finally stood up, and walked into the kitchen, still laughing and holding his ribs. "I wasn't ready for that." He said between chuckles.

"It really wasn't that funny." I pointed out.

He shook his head, "Your delivery made it unexpected." He downed a glass of water, and then took a breath to calm himself down again. "Anyways, what specifically are you comparing? Dragon fire would be an obvious one, but I don't think there's anything special about the Incendio charm... There are other types of magical fire, but I don't think that have anything mastery-worthy to study." He paused for a moment, "Phoenix fire is worth a study, but that requires a Phoenix." He looked at me expectantly.

"If I had a Phoenix, I wouldn't have taken the damn Knight Bus."

"Fair point." He acknowledged. "Different types of Dragons then?"

I shook my head. "Nope. All Dragon-fire is of the same type of magic, at least of the breeds that have been studied. I don't know enough about them to go studying new breeds, though."

"A bit too dangerous, that." Matthew agreed.

"Very much so." At his questioning look, I continued. "You're missing an obvious answer here."

"Obvious?" Matthew's eyes widened. "Fiendfyre?! Are you insane?"

"Not at all. I'm talented." I dryly responded.

"But Fiendfyre is Dark Magic! Not the Ministry, hand-slappy dark magic, but literal soul-damaging Dark Magic!"

"That's incorrect, actually."

He sputtered. "What?"

"Fiendfyre is actually 'Ministry, hand-slappy Dark Magic,' as you so eloquently described. I've studied it, in both what it creates and what its Arithmantic formula is. Dark Magic has similarities in its formula, in that the formulas strictly speaking are missing something. They require an additional sacrifice to work properly. Most Transfiguration is like this, actually, with the sacrifice being the original material. That's why conjuration is so much more difficult. It's also why people who do conjure items, vanish them as soon as possible. It's an old superstition. People are afraid of leaving bits and pieces of themselves around."

"Is that how it actually works?"

"Unlikely, but people aren't honestly sure."

"Wait. What about Charmed conjurations, like the bluebell flame?"

I laughed, "That's where things get really weird. The Arithmancy for those all check out without any additions."

"But you can't just pop things into existence without Conjuring. That doesn't make any sense."

"Correct. The theory here is that there is another dimension that we call the items from. Likewise, banishing an item will put it back into that dimension. This is opposed to Vanishing, for properly Conjured items, where there's again a loose end in the numbers, this time opposite to the Conjuring formula."

"So the people who go around Vanishing everything they Conjure might have a point."

"Potentially. I prefer Charms anyways, so it matters little to me."

"How does this apply to Fiendfyre?"

"Fiendfyre, in the Transfiguration and Charms debate, is effectively a Charm, so-"

"Fiendfyre, the seemingly living fire that eats everything, comes from another dimension." Matthew deadpanned.

"That's the theory behind it, yes."

"Right." He stood up from the couch. "That's terrifying."

"I try not to think about it too hard." I added as an afterthought.

"I can picture it now. You're at the dinner table with your family." He continued in a higher pitch, "'What did you learn in Arithamncy today, sweetie?'" Matthew snapped back to a deeper, deadpan voice. "'Fiendfyre is actually on loan from Hell.'"

I couldn't help it. I burst out laughing.

Matthew gave me a sideways glance. "You're laughing because I'm not wrong. You're laughing because leaders in your field agree with me. It's not funny, Daniel. It's terrifying."

I only laughed harder.

"I like Herbology. It's not terrifying like Arithmancy, or Charms." He paused, "Or Transfiguration, for that matter. It's just plants and sunlight and-"

"Devil's Snare." I finished for him.

"What?"

"Devil's Snare. It hates sunlight and chokes you until you stop moving. More accurately, it squeezes until it thinks you're dead."

"We don't talk about Devil's Snare." Matthew muttered.

"Exactly. Charms Masters don't talk about the fact that most terrible curses are just Charms with no redeeming uses."

"The Unforgivables?"

"Nope. Those are actual Dark Magic. Amusingly enough, so is a lot of healing. There's a reason that most healers have Unicorn Hair wands. The Unicorn Hair provides the extra energy required, and when it's all used up, the wand dies."

"I thought Unicorn Hair was just fickle."

"Most people do. The Wandmakers know better, but you're not going to explain advanced Arithmancy to a child, so the knowledge isn't generally passed on to the public."

"We're off-topic again. Do you cast Fiendfyre?"

"I do indeed."

"I thought it was a huge power drain."

"It's not." I corrected him. "It requires force of will, but not exceptional magical power."

"Hold on. The Patronus Charm. Isn't it-"

"It's technically a Conjuration." Matthew closed his jaw with a click. "They call it a Charm because they're stupid." He scoffed at me. "It's not actually a Charm. You're not displacing something; you're creating a semi-physical representation of positive emotions to act as a barrier. It's Transfiguration."

"That makes no sense."

"It's from the Ministry. People who don't know what they're doing are given power over how to package information. It doesn't affect you as much because plants aren't political, but spells are. Obliviation is terrifying, but it's qualified as a Charm. It's technically Dark Magic. You are stealing something from your victim that they cannot retrieve. But the Ministry has to use it, so it's classified as harmless."

Matthew shook his head. "Enough of this. Back to Herbology." I snorted. "There's a common rumor that Fiendfyre makes the best fertilizer..."

I shrugged. "I have no idea about that."

His eyes lit up. "Can we go find out?"

"Now?"

"Only if you're feeling up to it." He hedged.

I sighed. "I did eat about a pound of your mum's pasta. Let's go."

He whooped loudly, which I ignored in favor of summoning my shoes. "Do you have a place in mind? It should probably be mostly plant matter. I doubt that melted metal will be what you need."

"There's a huge compost pile I dump stuff into."

"No one else will miss it?"

"It's periodically burned anyways." He responded with a shrug. I got the feeling that he wouldn't care too much either way.

I stuck out my arm. "Ready when you are." He'd barely laid a finger on me before we were popped out of the apartment.

I sneezed as soon as we arrived. "That smell is terrible."

"You get used to it."

"I'd rather not, if it's all the same to you." I replied from within a Bubblehead Charm.

He snorted, and then glanced at my spell. "Is that a Charm?"

"It's a Conjuration. Semi-permeable membrane to allow oxygen, nitrogen, and hydrogen through. It also vanishes carbon dioxide."

"How?"

"No idea."

He shook his head, and then gestured to an enormous pile of rotting vegetation. "Here it is!"

"Do you want me to do all of it?"

"Can you?"

I gave the pile a look over. "Yeah."

"Is it safe?"

I rolled my eyes. "Now you ask?"

He winced. "I was excited."

"Yes. It's safe. Get behind me." He quickly did so, standing about twenty feet away from me.

I took a deep breath, centered my magic, and let the flames out to play. Light engulfed the area for a split second before it dulled to a bright glow. The super-heated waves of fire swept over the entire pile, with the turtle making an appearance repeatedly, seeming to swim through the waves or glide just over them. I felt the strain on my magic as the compost quickly diminished, but I let the fire dwindle down with its fuel source. Eventually, we were left with a much smaller turtle, and about a cubic meter of compost. The turtle lept high into the air before disappearing into the last of the fire, which then disappeared entirely. I took another deep breath.

"Holy buggering fuck! That was insane! You took out a hundred cubic meters in thirty seconds!"

"It's Fiendfyre."

I turned to look at Matthew. He had a bag in his hands, and he was summoning the remains into it quickly. "I thought Fiendfyre was supposed to take on the form of a mythical creature?"

"It is. Mine is a turtle. I have no idea why."

"That little jump at the end was ridiculous."

"Yeah. He's a character."

"He?"

"The turtle."

"You didn't tell it to do that?"

"No. He's a cheeky little bugger."

Matthew blinked. "Have you named him yet?"

"What?"

"The turtle. He's clearly your pet. You should name him."

"Why?"

He shrugged. "If the Charms theory is correct, then that turtle is a real thing that lives somewhere. You use him every now and again, but he exists outside of this plane, too."

"So I should name him?"

"I think you should."

"You're just feeling charitable at the moment because of the fertilizer." I pointed out.

"Probably, but I need to run tests on it. I'll see you back at the house." He popped away before I could stop him.

"Fuck." I muttered to myself. I had no idea where I was currently located, and had nothing but the bright light of the summer moon to give me any ideas. Looks like I was going to have to use line-of-sight Apparation until I got to a road, and then call the Knight Bus. Again.

"Fuck."

"Hey, Daniel. Did you stop at the store?" Matthew didn't know that he was about to die.

"I'm going to murder you." I calmly replied.

"Why?" He still hadn't looked up from his work.

"Because you made me take the Knight Bus, Matthew."

"Huh?" came his eloquent response. "I thought you could Apparate."

"I can't picture things in my head, Matthew. I can only Apparate with line-of-sight."

"Could you stop saying my name like you're going to kill me? After what you did to that compost, it's unnerving." He saw the look on my face, and began to backpedal. "I'm sorry about the Knight Bus thing, but you didn't warn me beforehand. I didn't know that you couldn't just pop back here."

"Stop being logical and let me throttle you." I muttered.

He learned back over his desk. "Just as soon as I finish this analysis..."

I huffed at him, before plopping down into a chair. "What are you testing for?"

"Just about everything. All of the standard fertilizer components, magical residue, all of it."

"What's the magical residue read?"

"Not Dark Magic at all, which is alarming. It's pretty much a neutral reading, like you'd get from a Niffler or something. It's very nutrient-dense, and with the high level of magical residue, it might all snap to if I tell it to."

"In layman's terms?"

He stood up straight again, stretching his neck as he did so. "There are spells that encourage neutral magic to become growth-based, to encourage the plant to grow. The spells can use the magic of the caster, but obviously it's much more efficient if you can take neutral magic and convince it to help you out instead."

"How willing is that magic?"

He shrugged, "I'm about to find out." He pointed his wand at a sample of the dirt, muttered something under his breath, and then flicked it wand upwards, and then downwards to its original point. The dirt practically glowed bright green.

I heard Matthew gulp. "The magic is very, very willing."

"Good." I said as I got up again. "I'm going to get some work done tonight. I still have plenty of spells to break down and build back up.

"Good luck." Matthew said absentmindedly as he continued jabbing at the dirt.