I wrote this back in May of 2018. At the time, I hadn't gotten very far into watching Zexal. However, this au came to me and I wanted to write this part. At the moment this only has one chapter. Now, I've finished watching Zexal, and there's a chance I might write more of this some day. Not guaranteed, but a chance. According to my original author's notes, this isn't a straight up role reversal au, since it's not Yuma and Kite straight up switching places, but it's something adjacent to that. I hope you enjoy!

Kite has never lost a duel.

Kite can never lose a duel.

Yet, as Kite stares at the opponent across from him, he might just have to admit defeat. His opponent has a monster, some sort of XYZ Monster known as a 'Number'. Apparently, only Numbers can destroy other Numbers, making any other monsters seemingly worthless against them. And of course Kite doesn't have a Number, how could he? He's never seen these things before. He had no strategy beforehand to take on something like this, and he's not sure the cards in his hand right now will do the trick.

Kite can't lose this duel. He has to keep dueling, to figure out how to restore his brother's memories. Somewhere deep down, Kite can feel that dueling is the answer. And maybe it sounds silly, and maybe he usually wouldn't act on a feeling like that, but for Hart, he'd try anything, do anything. He can't lose, but as Kite stares at the Number in front of him, he reflects that he might not have a choice.

And then, his extra deck glows with an almost blinding light. Squinting, Kite checks it. The monsters he already owned are there, waiting for the overlay network, but there's a new addition: Number 39, Utopia. A Number card? When did this get here, how was it here, why did he suddenly have a Number?

"Do not give in just yet."

Kite turns his head to face the voice and nearly jumps out of his skin when he sees the glowing, blue person floating next to him. Floating? What?

"Take note of Utopia's rank and abilities," the newcomer says. "You can use it to turn the situation around. Don't give in just yet."

"Are you going to make your move or what? Are you finally giving up?" Kite's opponent taunts.

Wait, can his opponent not see this new person? Kite grits his teeth, but lets it go. There's more important things right now. He looks over the card data for Utopia and realizes the newcomer is right. He already has on his field what he needs to summon Utopia. And if he plays his cards right, he can do this. Utopia didn't necessarily fit his deck theme, but now's not the time to worry about that, either.

"I overlay the two level four monsters on my field to build the overlay network! Come on out, defender of peace, Number 39: Utopia!"

Utopia appears on his side of the field, and it's a matter of seconds before Kite's won the duel. He turns away from his opponent and shoots a grateful smile to the newcomer. Kite wasn't always the most outgoing, friendly person, but he knew how to accept help and give thanks when the situation called for it.

"I don't know where that Number came from. But if it weren't for your help and encouragement, I may not have won that duel. Thank you. May I ask who you are?"

"There's no need for thanks. I did not do all that much, but...you're welcome, I suppose." The newcomer's expression doesn't shift from its current neutral. "My name is Astral. But...I'm afraid that's all I know. I appear to have lost my memories."

"Lost your memories?" Kite frowned, bringing a hand up to his chin in thought. "My brother, Hart, lost his memory not too long ago as well. Do you think it might be related?"

"Perhaps. I cannot say for sure, but if your brother shares in my plight, and if me getting my memory back restores his as well, then I will be happy to help." Kite blinks, and suddenly Astral's holding a card in his hand. The Number card that belonged to his opponent. "I believe my own amnesia is related to these Number cards."

"The Number cards?" Kite repeats. He stares down at Utopia, in his hand. "What do you mean?"

"When you defeated your opponent, I was able to recover his Number card. And when I did, I regained a memory, though it doesn't seem to be a very important one. Therefore, I can conclude that collecting these Number cards will help me regain my memory," Astral says.

"And maybe, if we get your memory back, Hart will get his back as well," Kite adds.

Astral nods. "And if not, then I'd be more than happy to help you find an alternative solution."

"It's settled, then," Kite decides. "I'll help you collect these Number cards, so that you can remember everything again.

Yuma's been acting weird, lately. Even for Yuma.

He's just...not himself. Usually he's happy, and carefree, and chattering away about some duel or another even though he knows he's not supposed to be dueling. But Kari can count on one hand the number of times she's seen him smile in the last week. He hasn't cracked any jokes in the same amount of time, and though he's probably still dueling, Kari's seen him go out with his duel disk, he doesn't talk about it. It's like Yuma pulled a total 180, and Yuma doesn't do that, even when he's got something on his mind or something really ticked him off.

His friends don't know what happened, and they don't know what to do about him. They've basically stopped hanging out with him altogether until he's back to normal, and Kari doesn't blame them. She'd do the same thing if she could, but she can't exactly stop being Yuma's sister. And...she's too worried to let this go. To just let this solve itself. Her fingers itch for a keyboard, she wants to figure this out and get him back to normal. She might not always show it, but she loves her little brother, and she misses him. The real him.

He has to still be dueling, she's sure of it. Maybe not as often as usual, but he still keeps his cards with him. Kari remembers one of the last conversations she had with her parents, these days it's echoing through her mind constantly. Mom and Dad told her that Yuma was going have a great destiny as a duelist someday, that he would be a great duelist, but that destiny would lead to danger, and dueling itself would become extremely dangerous. Was this what they'd been warning her about? It was impossible to say, they couldn't exactly confirm it themselves after disappearing. They'd told Kari back then to look out for him, and keep an eye on him. One thing was for sure; Kari had done a pretty poor job of that recently. Not for lack of trying, but just look at the results!

She was supposed to look out for him, and clearly she failed. This was on her. If anyone was going to help Yuma now, it had to be her. She had to make it up to him.

Duel records were relatively public information, and when necessary, one of the easiest sources of information to hack into. If Yuma was still dueling, maybe it was related to his sudden change in personality. So Kari did what she did best, and began to investigate. Yuma's duel records took only minutes to find. She could see all of his duels here, along with when they took place, who his opponents were, what cards were used, you name it. Even some footage of some of the duels was saved here.

Even if he wasn't himself, Yuma was still dueling almost every day. Kari pulled up the details on his most recent duel.

She doesn't recognize the opponent. She does, however, recognize a lot of the cards Yuma starts out with. He's still using the deck he got from their father. She's not much of a duelist herself, but she remembers the cards well enough from when her dad used to use them. But as she's scrolling through, something catches her eye. It's a card played by Yuma, Number 96: Dark Mist. Their father didn't have it, and she's pretty sure she's never seen Yuma with it, either. Not too long before that, Yuma's opponent supposedly played another one of these 'Number' cards.

Why do they have the same type of card? Kari keeps digging, and sees that all of Yuma's opponents recently have these 'Number' cards as well. Could this be a coincidence? On a hunch, she looks specifically into the Number cards.

Number cards only began surfacing recently, she sees. But now they're practically all over Heartland City. There's been some reports of people using these cards and behaving strangely afterwards. Was this what was happening to Yuma?

Kari tabs back over to Yuma's duel record, briefly, and swears under her breath. He's dueling right now. When did he leave the house? Whatever, no time to think about that now.

Without hesitating, Kari runs out, jumps onto her motorcycle, and heads over to the duel's location. It's not that far away, and with the motorcycle's speed it doesn't take long to get there at all. Once she arrives, she parks the motorcycle quickly, throws off her helmet and jumps off. It doesn't look like the duel has been going on for very long, but Kari has a feeling it won't go on for much longer, either. Some of Yuma's recent duels were over in a few turns.

"Yuma! What the heck are you doing?" she yells out to him. "You know you're not supposed to be dueling, right?"

Yuma ignores her, doesn't even look at her. Instead, he just talks over her like she's a distant lawnmower. "-and build the overlay network. I XYZ summon Number 96: Dark Mist."

There it is again. This same monster, summoned in duel after duel. Kari has a bad feeling about this.

"It's only got 100 attack points! What's a puny little monster like that gonna be able to do?" His opponent taunts. Yuma just rolls his eyes, like he's heard this a hundred times before, sets a couple of face downs and ends his turn. The whole time, Yuma doesn't smile once, doesn't make a single joke or pun, and he goes through it quickly, like he can't wait for this to be over with.

His opponent goes in to attack, and Yuma just sighs. "Number 96's effect activates. By removing one overlay unit, your monster loses half of its attack points, and Number 96 gains the same number of attack points." His opponent's monster loses the battle and is destroyed.

The look in Yuma's eyes right now is terrifying.

From there, it's only a matter of seconds before the duel's over, Yuma winning once again. Yuma smiles, the first smile Kari's seen from him in days, but her heart drops. That's not the joyful smile of a kid enjoying a duel. This is more...sinister. Malicious, almost.

"Another Number to add to my collection," Yuma mumbles to himself, approaching his opponent.

Kari doesn't think, doesn't hesitate. She just acts. Before she even knows what she's doing, she punches Yuma in the face, hard enough to knock him out.

"Sorry, Yuma," she says as she picks him up. "But this isn't you. What happened to you, bro?"

"Sounds like he's been possessed by a Number. And a pretty nasty one, too."

Kari whips herself around and finds herself staring at Mr. Heartland himself. Her eyes widen. "You know about the Numbers?"

"Of course I do, they've been making quite a mess of the city! I'm hoping I can find a way to stop all this before it starts to put people into a panic," Mr. Heartland responds.

"Does that mean you know how to help Yuma?" Kari frowns, looking down at her brother's face. "He hasn't been himself lately. It has to be related to that Number card. I don't know what's going on, but I want my little brother back."

"I can't say for certain, but, hmm..." Mr. Heartland tilts his head to the side. "These Number cards are pretty strong, and I suspect that the one your brother picked up might be one of the more powerful ones. But if we can overpower it, maybe we can free him."

"Overpower it? How're we supposed to do that if they're so strong?" Kari asks.

"With other Number cards, probably," Mr. Heartland answers. "If we collect enough of them, it just might work."

"I can help," she offers immediately. "If it'll bring him back, I'm willing to try anything."

"Then how about this?" Mr. Heartland proposes. "I'll make sure your brother is looked after. We'll keep him safe, and you can see him anytime you want. But we'll make sure he doesn't start any problems, either. We'll keep him from dueling, and any other trouble he might try to cause. At the same time, you start collecting Numbers. Become a...a Number Hunter, if you will. If you don't have your own deck, you can probably use your brother's, and we can find a strategy to take down Numbers one by one. You won't have to collect them all yourself, you'll have help, I promise you. When we have enough, then we'll try to free your brother. And while we're at it, maybe we'll help everyone else in the city possessed by Numbers, too. What do you say, do we have a deal?"

He holds a hand out to her, offering a handshake. Kari stares up at him. Would this really work? She had to believe it would. She reached up and returned the handshake. Mr. Heartland smiled.

"We have a deal," Kari tells him. Once more, she examines Yuma's face. He had to still be in there, somewhere. "Hang on, bro, you'll be back to normal soon."