Title: Simple Arithmancy
Author: JoeHundredaire
Rating: PG-13/FR15
Disclaimer: J.K. Rowling owns the Harry Potter universe. Wish they were mine so I could do increasingly nonsensical things to them and watch my bank account get steadily larger, but sadly not mine. Like the Marvel universe, the DC universe is a copyright nightmare due to creator ownership battles and the like even if you're just going to cherrypick from one specific movie. Not mine, don't sue, et cetera and so forth.
Summary: "3X2(9YZ)4A!"
Joe's Note: After breaking new ground with the last chapter, I think I'm going to revisit it by taking Luna out of the wizarding world in this chapter, too. Mostly because… well, every chapter has involved her gaining a level of power that leaves little in the magical world to challenge her. That's kinda been the fun so far. But this is the fifteenth chapter of this story and so I figure doing something a little different for at least two of the chapters - technically three if you consider that Luna never makes it home in The Seventh Siren - is a nice change of pace. That and I'm a religious watcher of The Flash each Tuesday night with my fiancée, so it's nice to finally dip my toe into a universe that I enjoy but haven't had a reason to work with too much yet.
Dedications & Thanks: To Nicholas, Howard, Jade, Alexander, Tibor, Alonsis2, Daniel, Clark, Adrien, erlking, ridillin, Haematite, Charles, Jacky, Edward, Andrew, Roofcrawler, Wil, PbookR, Samuel, Mikey, Beverly, Daniel, Charles, Crygon20, Subtle, Christopher, Stephen, Fablesrogue, Morgan, Joseph, Jason, RileyWestfall, bloodylord, Marc, Ziryo, Chris, George, Koby, William, Devin, JJbelle, David, Gavin, TheTenthAncestor, Lookshy, Mauday, John, Roman, Warren, and Jess for sponsoring me on , and making it easier for me to spend more of my time writing.

The Room of Hidden Things certainly had a lot of things hidden in it.

That was the sole thought running through Luna Lovegood's head as she wandered along the narrow pathways that wound back and forth through the overwhelming piles of junk that surrounded her. The room was easily the size of the few cathedrals she'd visited in her travels with her father, and filled practically to the rafters with… well, junk. The framework for the piles was largely furniture; given that house elves could repair or vanish things on behalf of the school, she suspected that it had all been brought here by students to hide the evidence of spells miscast. Although that begged the question of how they'd managed to move entire bed frames, bookcases, and desks from their dorms or otherwise abandoned classrooms to the Room of Requirement.

Scattered here and there around the room stood leaning towers of cauldrons, most of them heavily stained from usage. Luna found them more than a little intimidating; one wrong touch could leave her buried under a painfully heavy pile of metal. There was also the fact that many of them were still dripping some unknown - and presumably failed - potion. Nothing said 'long visit to the hospital wing' like getting doused in one or more misbrewed potions.

Beyond towering stacks of cauldrons and damaged furniture of all shapes and sizes? There were also thousands upon thousands of books of every shape and size, enough to make her inner Ravenclaw swoon. They were packed into bookshelves: some stacked into piles, and others crammed in between other things as if a student in a hurry had simply stuffed it into the first available space before running off again. Given the visible age of some of the books, she wondered how many of them had since been banned by the Ministry of Magic… or were perhaps hidden here by students who coveted already forbidden knowledge.

And then there were the miscellaneous items that were just plain junk. From where she was standing alone, she could spot at least three different sizes of winged catapults, a pair of Fanged Frisbees, several dozen bottles half-filled with congealed potions, what were quite possibly the pieces of two different species of dragons' egg shells, several rusting swords, an imposing axe still stained with blood, several different Hogwarts uniform hats, some cloaks, a rather lovely silver and sapphire necklace that she was quite probably going to nick for herself if she could ensure it was safe to wear, and no small number of bottles of alcohol that had been consumed to varying degrees.

Forget her intention upon entering the room - she'd been in search of an interesting way to wile away an afternoon - she could spend years exploring the Room of Hidden Things and still not uncover all of its secrets. But seeing as she had a few hours at her disposal? She could at least do her best to scratch the surface.

As a Ravenclaw, her first draw was understandably the books and so they were where she decided to turn her attention first. Three separate attempts at a Summoning Charm failed and so Luna let out an aggravated huff as she dragged a rickety but stable enough chair over to rest near one of the piles of books. Plopping herself down on it, she grabbed the top book off the pile and checked the cover. Herbology text. Not quite her bag. Pass. Treatise on the mind arts? Perhaps something that Harry could use, given his ongoing difficulties learning occlumency. That one went into the bag she'd set down at her feet. The next two books were also herbology-centric - making her wonder if this particular pile was a single individual's dumping ground - and then came a mysteriously nameless book. She ghosted her fingers over the black cover, tracing the embossed golden lightning bolt that adorned the otherwise featureless text. This was one book that she certainly couldn't judge by its cover.

It turned out to not be a text of any kind, but rather someone's rather extensive notes in the field of… arithmancy, it appeared. Or at least that's what Luna guessed it was, given the complex equations scrawled down each page, stretching on for page after page. It looked far too complex for her Hogwarts peers, especially based on what they'd covered in her Arithmancy class thus far… and were scheduled to cover in the next two years according to the few older Ravenclaws willing to deign to talk to her about her second favorite subject. She flipped back to the inside of the front cover and then moved onward to the back cover; neither was marked with anything that might possibly identify who the book's author was. So who had left this book behind in the Room of Requirement? Why? For that matter, why had they written out… all of this? What were they researching? What were they trying to accomplish? Had they ever achieved their goal?

Flipping to the last page in the book, Luna's eyebrows rose at finding a sequence of numbers of letters written in a large hand and circled twice in red. Apparently they had solved whatever problem they were tackling. Although it appeared that her initial assumption that it was a book of arithmancy calculations was in error, she mused, because unless it was something extremely advanced that would be introduced during her NEWT years? Which was certainly possible but unlikely given what she knew about the subject? Arithmancy only used numbers, not letters.

"What kind of question are you the answer to? 3X2(9YZ)4A?"

Nora West-Allen was having one hell of a day. Her father Barry was still trapped in the Pipeline, a victim of the latest meta-tech's abilities. Unable to control his phasing abilities, they'd have to deprive him of his powers completely to prevent him from phasing his way all the way through the planet… and then presumably out the other side and into space? Cisco hadn't really covered that eventuality, although Nora had a thorough enough grounding in their shared powers to have some idea what might have happened if they hadn't neutralized his connection to the Speed Force.

From there, Nora had been forced to take her father's place on the stand in the trial of Joss Jackam and had managed to successfully stumble through enough testimony to put the meta-tech user behind bars. The defense had tried to trip her up by arguing that the tech had been to blame more so than Joss herself, but Nora had managed to recover and convince the judge otherwise. A new meta-tech user who they were tentatively calling Silver Ghost had managed to break Joss out, but Nora had rounded the young woman back up and turned her over to CCPD.

But unfortunately the case of Joss Jackam - who was quite possibly actually going by Weather Witch at this point - wouldn't wait for her dad to recover. Because while Nora had turned the young woman back over to the police earlier that day, she'd been broken back out by the same woman as the first time. From there, the duo had teamed up to steal an extremely high-tech prototype car from ARGUS, and now they were running wild through Central City with it.

And Nora couldn't help but feel as if things were partially her fault. Joss had come to her, claiming that her 'breakout' was more of a kidnapping and asking for help turning herself back in. Offered to turn on the Silver Ghost, even, and lead Nora back to her hideout. But not believing her to be sincere, Nora had turned around and dumped her off with CCPD, leaving her to face the music for a jailbreak that she claimed she hadn't instigated. Of course Joss would have turned to someone else after being betrayed by Nora; when the hero wasn't willing to give someone the time of day, what option did that leave them?

With nothing left to lose, Nora decided to take advantage of the open radio channel that Cisco had established for her to try and make one last appeal to Joss's better nature. "Joss? Joss, it's XS. I hope you can hear me. You tried to tell me something earlier. You tried to tell me you wanted to pay for the crimes that you committed. You said you weren't a criminal like your father. You asked me to give you a second chance, but I didn't listen! Now I'm asking you for a second chance. Joss… this isn't who you are."

"While that's very heartwarming, there's an easier way to find who you're looking for." Nora gave a start at the unexpected voice, turning to find a young blonde in a sleek blue and bronze suit standing next to her. Raising her right hand, the girl thrust the stick she was holding skyward. "Homenum revelio!" There was a visible ripple of… something… moving outward from the tip of the stick, and Nora looked back and forth uncertainly. Then down at the end of the street and moving closer was a ripple… a ripple that looked suspiciously similar to the car that Nora had been chasing. "There we go. We found them. Now what?"

Turning back to the unknown blonde, the questions tumbled from Nora's lips in a torrent of confusion. "Who are you? Where did you come from? How did you do that? Why are you helping me?"

The blonde offered Nora a quirky little smile before using her stick to gesture to the still oncoming car. "I could be wrong, but I feel like the answers to all of those questions can wait until after we're done here. But if you're not up to dealing with that… reducto!" She whipped her arm forward, hurling a larger bolt of blue energy wreathed in blue lightning at the approaching car. It smashed into the hood, caving it in and sending the car spinning out of control until it crashed into an unlucky car parked along the side of the street. Before Nora or her newfound ally could react, the sunroof retracted and both Joss and her cohort were carried away by a brilliant white bolt of lightning. "Well bother."

"Hey, we managed to stop the killer car even if we didn't manage to capture either of them. I'll still call that a win." Nora jetted forward in a blaze of purple and gold lightning to secure the car, only to be caught by surprise again as her companion followed with her own matching crackle of blue lightning. Turning to face the blonde, Nora raised her hands. "Okay, now I really need answers to my questions because I'm having all new ones to add to the list. You're a speedster? Because you're definitely not Trajectory and according to the Flash Museum, she was the only female speedster in this time period other than Jessie Quick. And the only one with blue lightning."

The blue lightning crackled around the girl again before dying with a fizzling pop, making the blonde pout as she looked down at herself. "Well, at least you picked a good time to die for once. 3X2(9YZ)4A!" The girl arched her back as blue lightning rippled and surged over her body before fading away as she let out a sigh of relief. "Ahh. Much better." Reaching up, the blonde gathered her nearly ass-length blonde hair into a ponytail - and how she could run at any real speed with hair that long, Nora had no idea - before raising an eyebrow. "So, you said this time period? Does that mean you're familiar with more than one?"

Nora blushed faintly, running her hand through her considerably shorter hair before nodding. "I'm… kinda from the future. 2049 to be precise."

"Fascinating." Reaching out, the blonde offered Nora her hand. "And just so you can stop thinking of me as 'the blonde'… oh, don't look at me like that, everyone thinks in terms of adjectives when they don't have any other way to refer to a person. As I was saying, my name is Luna. Luna Lovegood. I don't have a fancy name like you and all the other speedsters do yet. Maybe we can figure one out over coffee?"

That brought Nora up short. "You want to go get some coffee with me?"

Luna's quirky little smile abruptly widened. "Are you asking me? Because I'd love to. You're much cuter than I expected based on the pictures in the paper. They're usually fairly blurry, especially in the face. I thought maybe you were hiding some sort of disfigurement or something. But you're not. You're lovely."

Blushing darkly, Nora reached up to tap the side of her head. "Guys? I've got good news and bad news. Good news is that we've got the car. Bad news… I may have messed up the timeline more than we thought I did."