A/N: What's with all these AU ideas? XD Anyway, here's a demon hunter AU (or, perhaps, a Devil May Cry AU since that's where the inspiration came from?).

DISCLAIMER: I do NOT own Yu-Gi-Oh! 5D's. That goes to the respective owner. I only own my OC(s).

Demon Hunter AU- Just Another Day:

(Yusei's POV)

"Okay, the target has been located. All we need to do is take him out," I said.

"How do you know the target is male?" Ren, my partner, asked.

"Are you really going to start an argument right now?"

"Come on, you should know how I am." He added the comment with a grin, displaying the long canines of his.

"If you cause this guy to get away, I'll be convinced that your demon half is an imp."

"Aw, I'm hurt. 'Sides, he's not gonna leave."

"Do I want to know what you're planning?"

"Probably not."

"That's what I'm always afraid of." Truth be told, I still have no clue how we became partners. He's more unpredictable than the other demons we've fought and killed in the past (and that's saying a lot). Plus, other than his display of creating and controlling fire, I have yet to see any other abilities from him. Honestly, I'm a bit nervous about what he hasn't shown.

Once we got near the building, I heard a grunt from Ren. "That's better."

"I swear, it gets weirder each time you pull your tail out from hiding," I sighed.

He snickered. "Well, can't have my tail out all the time. I doubt other humans are going to like seeing something inhuman."

"Whatever." I pulled out my gun from my holster.

"Dude, seriously, why a gun? You can use magic, right?"

"Ren, we're not discussing this right now."

"Uh, yeah, we are. Like seriously, you're supposed to be a-" He didn't get to talk too much as the doors were blasted open by a giant demon, sending Ren flying into a parked car on the other side of the empty street.

"Ren?!"

I could vaguely hear him groan out, "Yep, just made my shit list," when the demon hissed out.

"Filthy halfbreed son of a traitor!"

"My my, quite the ruckus here," the target mused. "Didn't expect someone like you to team up with a half-demon."

"Yeah well, can't exactly get all of my jobs done alone." I slightly turned my head, keeping a close eye on him as well as my gun trained on him. "Ren! You take out the big one! I'll take the target out!"

"Fine then. I need to cut this guy down to size anyway." He pulled out his knife which started sparking before becoming the large clay-more he wielded. "Hope you won't miss your legs back in hell!"

While Ren dealt with the larger demon, I started firing at our target. Each bullet missed as he dodged. Damn, he's a lot faster than I thought, I cursed inwardly, already having to reload. Right as I did so, however, I felt claws slice across my shoulder. Said arm went limp for the moment, my magic starting to heal the injury. Shit! You've got to be kidding me! Using my good arm, I kept firing, trying to hit him.

(Ren's POV)

"How...How could I lose to a half-demon?" the large demon grunted. He let out one last roar as I stabbed him.

"Well, as they say, the bigger they are the harder they fall," I said, pulling out my sword once the demon stopped moving. I caught the sounds of gunshots. "Still? Geez, it can't be that hard to hit one little demon."

I walked into the building. My eyes went wide at Yusei who had multiple gashes (the wounds sparking to show his magic was trying to heal them) and missing each shot at the demon. Okay, maybe this demon is a step above what he's used to. Ugh, I hate the speedsters. Luckily, I know just the thing to slow one down. I changed my clay-more back into a knife, putting it away as I let the fire magic activate in my hand.

(Yusei's POV)

Dammit...how the hell do I defeat this guy? I thought. I couldn't risk losing any more bullets to his dodging. My strength was also fading with the blood loss. Even with my abilities, I wouldn't last much longer if something didn't change. If only I could get a shot in, then we'd be done here.

"Hey asshole!" a voice called. Ren?

A blast of fire magic hit the demon in the leg. He let out a screech. "You little whelp! How dare you!" he growled.

"Whatcha gonna do about it, pal? I've got plenty of magic to spare," Ren taunted, a hand still coated in flames.

"Your magic won't do you any good if you're dead!" He darted to Ren. Ren, move! What the hell are you doing?! I tried to bring up my gun, but I wasn't quick enough as the demon managed to reach him.

Ren looked like he tried to move. However, the target was faster and managed to jab his hand through Ren's shoulder. He grinned. "What do you say to that, half-demon?"

"I say...you speedsters are so easy to beat." He got confused until Ren reached up and gripped the arm. "Yusei, now! Shoot 'im while he can't move!"

"What?!"

That's what he was doing! I brought my gun up fully, took aim, and fired. The bullet finally hit home in the target's head. Ren pushed the body away, clutching the hole in his shoulder. "Agh, damn. Forgot how painful that could be," he hissed.

My magic managed to heal up my injuries and I rushed to him. "Why did you do that?! He could have killed you if you weren't fast enough!" I scolded, pulling his hand away to check on the injury.

"Well, gotta keep the guy still enough to hit. Besides, this will heal up by the end of the day."

I gave a sigh of frustration. Why did he brush off all these injuries like they're merely scratches? Half-demon or not, even he should know his limits. I guess there's one way to help this situation. "All right, this might sting then."

"What might- f***!" I activated a bit of magic into my hand and pressed it on his injury, causing the shout. With the differences in magic, mine would sting him rather than feel like nothing. I kept it on long enough to seal the injury, taking my hand off immediately. "A bit of warning would have helped!"

"Would you have let me?" He looked like he tried to retort something but stopped, closing his mouth. "Exactly. Now let's get going."

(Ren's POV)

"Fine, whatever," I sighed. Yusei's magic managed to heal the rest of his injuries, so he didn't need help walking back to our base. My shoulder would be sore for much longer considering he used said magic to heal it. At this point, I probably would have dropped our little deal. This is what I get for falling for an angel.

A/N: At this point, I'm going to be making so many AUs, they'll overtake all the crossover stories I've been trying to start XD

In other news, I'm having to update my Yu-Gi-Oh! 5D's/Voltron: Legendary Defender quite a bit as season 3 of Voltron: Legendary Defender has come out (with season 4 coming really soon). All I have to say is...I've got more questions than answers out of this season. I hope season 4 answers a few things!

Also, it's kind of funny that I have more stories for Ren than Aurora because the latter is actually my first OC (who also went through at least three last name changes since her creation). I guess it's 'cause Ren is more fun to write about XD

EDIT: I forgot to mention this but Yusei is not full angel (hence why he uses guns to fight demons instead of his magic). However, Ren does not know this as he's never had any contact with angels...because they would kill him simply for existing (he's half-demon after all). Just wanted to clear that up. I'll be writing a prequel to this soon enough to explain a few things (like how they met which will hopefully be hilarious).