WARNING: Gratsu is gonna go along sweet and slow so don't get your hopes up too much yet.

I do not own Fairy Tail

The two mages bickered all the way to their destination: their old fighting spot near the river. Natsu faced Gray before taking a battle stance, determination and anger in both of their eyes.

"ICE MAKE.."

"FIRE DRAGON…"

"HAMMER!"

"IRON FIST!"

The two mages went on the offensive at the same time and both blocked the other's attacks. Natsu crushed through Gray's ice hammer and met Gray's fist. Both mages were blown back by the force of the attack and the ice shards from Gray's hammer were flying everywhere, giving both boys shallow cuts. Natsu's eyes met Gray's before launching another attack.

"ICE MAKE CANNON!"

"FIRE DRAGON ROAR!"

The attacks continued to cancel each other out, neither getting the upper hand. Natsu and Gray could both feel their magic depleting and after an hour of exchanging attacks were nearly out of power. In one last frantic attempt to win the duel, Natsu readied his fire for one last intense iron fist attack. Predicting Natsu's attack from his fighting stance Gray decided his best bet to win the battle would be to use his new magic.

"FIRE DRAGON IRON FIST!"

"ICE DEVIL'S ZEROTH LONG SWORD!"

The boys ran at each other, one with a flaming fist and the other with a sword of dark ice. Natsu dodged under the first swing of Gray's sword and sent his fist into the ice mage's abdomen, sending the ice mage flying. Gray landed on his back and groaned in pain, unable to get back up and covered in cuts and bruises.

Natsu raised his fist in the air and whooped a tired cry of victory.

"HAHA take that ice princess! I won! I wo-" Natsu suddenly doubled over in pain, falling to his knees and letting out a blood curdling scream. His right arm felt like it was on fire! His eyes scanned over his arm and saw a small cut right below his shoulder.

What the hell?! I must have been hit by Gray's sword before I launched him. Holy shit it burns! Is this what it feels like to be on fire?!

The small cut on his arm had started oozing a black liquid and Natsu screamed again out of pain and terror. What the hell is happening to my arm?! The burning feeling began to spread from his arm to the rest of his body. He began to claw at his arm, almost wanting to cut the whole thing off. It felt as though his insides were boiling, slowly melting his entire body from the inside out. The pain was becoming too much, Natsu's vision began to blur and he barely registered the concerned voice calling his name before his vision went black and he fell roughly to the ground.

…

"Natsu! Natsu, what's wrong?!" Gray had been lying on the ground paralyzed when he heard his companion scream, a scream that had cut through him like a knife, a scream that rattled his very core. Desperate to help his rival, Gray sat up on one knee and tried to stand. His right ankle, however, gave out and he fell right back down again. Frustrated and desperate, he let out a groan of frustration and quickly crawled to where Natsu was kneeling, still screaming in pain.

Gray grabbed Natsu by the head and shook him a little.

"Natsu, what's wrong dammit!?" Tears were streaming down the dragon slayer's face and his left hand was frantically clawing at his right shoulder. Gray could see him weakening and it was mere seconds before Natsu let out one more strangled whimper and fell face-first onto the ground.

"Shit!" Gray tried to lift his rival up and turned him onto his back, inspecting his body for the cause of his pain. His dark blue eyes were drawn to the hand still on Natsu's right shoulder, right next to his guild mark. Black fluid seemed to be dripping through his fingers.

"What the hell?" Gray whispered in confusion. He gently removed Natsu's hand from his shoulder and gasped. The wound was shallow but disgusting. Black something leaked out of it and the edges of the cut were purple and swollen. Gray could see the claw marks surrounding the cut that were from Natsu's nails trying to claw out the fluid. The veins around the cut were bulged out and also turning darker purple. It seemed to be spreading, the cut getting worse each second. Gray quickly looked at their surroundings before his eyes landed on the grey shirt he had discarded before the battle. He crawled to it quickly before returning to Natsu and tearing the shirt into strips he could use to cover the gaping wound. One strip he folded into a square that he used to press against the cut and the other he haphazardly tied around his arm to keep the cloth in place.

Gray's thoughts were a mess. What even happened? This has never happened before, I don't understand.. This must have been from the devil slaying sword but...why..? Gray's eyes started to tear up upon realizing that this had been his doing. Shit! I'm such an idiot! I shouldn't have used my devil slaying magic, I don't have enough experience with it yet and I don't even know what it's capable of. Still Gray was confused. As far as he knew, this wasn't supposed to happen. Trying to remain calm, he attempted to rise again, annoyed when his ankle gave out once again.

Shit, I don't have time for this! I need to get to the guild now! Gray glared at his ankle before using his magic to make a boot of sorts out of ice. He stood back up and walked a few stiff steps with it, deeming it sturdy enough to handle the job. He turned back to Natsu and knelt, lifting the lifeless body onto his shoulders in a fireman's carry before slowly and painfully starting the walk back to the guild. It was about half a mile away but it seemed like a thousand miles for how fast he could hobble over.

Grunting in frustration and mild pain, he shifted Natsu on his shoulders and continued walking.

"Geez could you lay off the everything? You're so freaking heavy flame brain." Natsu let out a quiet grunt and Gray smirked. Wow even when he's unconscious he's still a pain in the ass. Seriously though, I'm gonna break my back carrying this idiot, I should've just left him on the ground by the river. I'm sure he would've woken up...eventually.. Gray mulled over the black stuff seeping out of his arm and the screams of pain he had heard earlier. Or maybe not.. With a renewed sense of urgency, Gray shuffled faster toward his guild and prayed that Wendy was in the guild hall.

…

When Gray reached the large wooden doors to Fairy Tail, he breathed a sigh of relief as he pushed open the doors with his body, his shoulders aching from Natsu's weight. As soon as he was through the doors, Gray yelled at the guild for help.

"WENDY?! HAS ANYBODY SEEN WENDY?!"

All eyes were on Gray at that moment and the entire guild filled with gasps. Everything was still for a moment before the barrage of questions began.

"What happened to Natsu?!"

"Is he OK?!"

"Wow Gray you actually won a fight for once?!"

"Woah it looks like his veins are about to burst!"

"Natsu!"

"Gray what happened?!"

"I think I saw Wendy in the infirmary in the back!"

Gray silently thanked whoever had given him the information he actually needed and limped to the back room. When he entered the door to the infirmary he saw Wendy tending to another patient on one of the beds.

"Wendy!" he gasped in relief. Wendy turned around and her eyes widened at the sight of Natsu on the ice mage's back.

"What happened? Is Natsu ok?!" Gray was too tired to answer and simply put Natsu down on the bed nearest him and clutched the side of the bed desperately, feeling as though he was about to collapse. Wendy noticed his exhaustion and quickly rushed to put a chair she had found next to another bed under him. The small sky dragon slayer then rushed to Natsu's side and began scanning his wounds. She noticed the bandage hastily wrapped on Natsu's shoulder and gently tugged it off, gasping in shock and disgust when she saw the wound hidden underneath.

"Gray what is this?" She asked quietly, examining what should have been a shallow and unseeming cut. The black ooze was still dripping out and the veins around it looked even more pronounced and darkly colored than before.

Gray kept his eyes on Natsu's face when answering. "I don't know. I cut him with my devil slayer's sword I think but I have no idea why it looks like that. It's not even a deep cut."

Wendy's hands began to glow as she used her magic to try and heal Natsu's wound, trying to find the source of the infection.

"Something feels weird about this. The wound feels almost like dark magic. And it's spreading. It's a long shot but I think I might have something that might work…" She turned around and walked to a nearby medicine cabinet, opening it and rummaging through a collection of ointments and bottles. Gray watched as she returned with a vial of liquid that was so white it seemed to be glowing. The small healer unstoppered the vial and poured half of its contents on the wound. The black ooze began to sizzle and let off a rancid odor. Gray let out a short yelp and quickly covered his nose.

"What the hell? What is that stuff?! It smells awful!"

"Hmmmm…" Wendy frowned and dabbed the excess blood and dirt off of the wound.

"Interesting.. Well this stuff is a solution I made shortly after I returned here from the Tartaros battle. It's a solution made by mixing my healing magic with light magic from the master. I used it to heal a lot of wounds that were caused by the demon curse powers-"

"But i don't understand" Gray interrupted, "my magic is demon slaying magic, it shouldn't have the same effect as the demon's curse power, it's supposed to destroy demon magic." Wendy finished bandaging the wound and tied it off before meeting Gray's eyes. Both of them were confused.

"I don't know Gray.. but I'm going to tell Master about this. Maybe it might be good to hold off on using your devil slayer magic until we do more research on it. You could always ask Levy and Lucy to help you research it, I'm sure they would be more than willing to help. And I will help you any way I can too!" Wendy gave Gray a big grin and the ice mage ruffled her hair fondly.

"Thanks Wendy, why don't we head to Master Makarov together and tell him what happened?" Wendy nodded happily in response and turned to leave the infirmary, Gray following close behind until he realized he still had a sprained ankle and fell unceremoniously onto the floor.

"Shit...oww.."

"Gray!" Wendy rushed to Gray's side frantic and asked what happened.

"I sprained my ankle during my fight with that idiot" he said, pointing an accusing finger at the unconscious dragon slayer on his bed. "I guess I forgot about it until now."

Wendy's eyes widened in realization, "you mean you carried him all the way here on a sprained ankle!?" Her look turned to that of admiration. "Wow! I only hope to be as strong as you someday!"

Gray chuckled softly. The little dragon slayer was adorable and he wished he could preserve her innocent and hopeful personality forever. It was a great balance to his own pessimistic behavior.

"Don't worry Wendy, after your ordeal with Face, I think you might just be stronger than me. Besides, without your healing powers, half of the guild would probably be dead." Gray winked at her with a smile and she blushed shyly at the ground. "As for this," he continued gesturing to his ankle still trapped in ice, "how about you just help me into a bed and go get Gramps to come in here so we can talk."

"Ok!" Wendy helped pull him to his feet and let him lean on her shoulder as they walked to the bed right next to Natsu's. He sat up on the bed and told Wendy to go get the master.

"I'll be back in a second Gray! I'll heal your ankle while we talk to the Master, I still have enough magic energy left, since the light solution did most of the healing for Natsu!"

With that, Wendy left the infirmary to go grab Makarov and Gray relaxed his head back onto a pillow, utterly drained of energy. He desperately wanted to go home and sleep but wouldn't let himself give in until he got to talk with the Master as well as Levy and Lucy about researching his magic.

He glanced worriedly at Natsu's still form to his left. He seemed to look better, his face serene and the veins beginning to recede back into his arm with a normal coloration. Still.. Something weird was going on here. I have a feeling there's more to this than we can see.. Natsu I'm so sorry, if it weren't for Wendy and her light demon magic destroyer potion thingy, I don't know what would have happened..

Gray's thoughts were interrupted by the sound of the infirmary door creaking open. Well that was fast..

"GRAY!?"

Oh shit.

An armor clad figure with long scarlet hair burst through the door. Gray immediately stiffened and sat up straight as a board, putting his hands in front of him to ward off any possible attacks.

"Listen Erza, I didn't know what would happen! Don't worry he's fi-"

"ENOUGH! I heard that you were seen carrying an unconscious Natsu through the guild! How dare you hurt your friend to such extreme measures, and in a petty fight no less!" Erza shot the ice mage a glare that could have killed him on the spot.

"Erza I didn't mean to I swear!"

"Explain. Now."

"Ok well we were fighting like usual," Erza tensed and Gray flinched before continuing, "and we were nearing the end of our fight both wiped out, when he punched me and sent me flying. He actually won technically, since I guess I was knocked out first, but don't tell him that cuz I don't want him to think he's stronger than me, I was really holding back and he was just being an idiot and if I had used my true power earlier I would have definitely won and I don't really know what happened but there's definitely something going on and we can just pretend th-"

"Gray! You're rambling! Get to the point!

"Well-"

"Ah Erza you're here too! Good, now how are you doing son?" Makarov and Wendy had just chosen to walk in at that moment and walked past Erza toward the beds where Gray and Natsu were resting.

Well I feel like I'm in an interrogation and I hurt literally everywhere. "I'm fine Gramps," he said coldly. He really just wanted to go home. Natsu was fine right? So what's the big deal? Yet Gray knew he better talk to the others about everything, if something happened to Natsu.. We may hate each other but I could never look at myself the same if I really hurt him, or worse killed him..

Erza seemed to have calmed down and grabbed a chair to sit by Gray's bed while he gave them all an explanation. Makarov went to sit on the left edge of his bed while Wendy began working on healing his right ankle.

"Well we were fighting as per usual and I don't really know what happened but I used my devil's slayer sword while he slammed me in the gut with an iron fist attack. I was knocked back and on the ground when Natsu started shouting about his victory and whatever." Gray clenched his fists and shuddered at the memory of his rival's gut-wrenching scream. "I don't know what happened but suddenly he started screaming.. I could feel his pain through his scream, it was awful." Gray's face was grim and he glanced at Natsu beside his bed, relieved at the sight of his relaxed and peaceful face. Erza took his hand, prompting him to go on.

"I crawled over to him and saw the wound on his shoulder. I must have cut him with my sword before he knocked me back. It was the ugliest wound I've ever seen, some gross black goopy shit was coming out of it and his veins were turning dark purple. There was a little blood but not much, it wasn't even a deep wound really.. He fell unconscious and I wrapped it up and carried him back here where Wendy took care of him." Recounting the story made him fill with guilt and the other's must have seen it because they all looked at him with pity.

Wendy decided to take over and interjected, "the wound was unlike anything I have ever seen but kinda reminded me of the dark wounds I had seen on those injured by the demon curse magic." Makarov and Erza looked at her in surprise.

"I used the light solution on him" she continued "and it worked."

This time both mages gasped, confused about how this could have happened.

"Are you sure, child?" Makarov asked, a look of deep thought plastered on his features. Wendy nodded her head.

"The black fluid on his arm disintegrated when the solution touched it. It was a similar reaction to the other demon wounds I healed." Wendy pat Gray's leg letting him know she was done healing and Gray gave her a look of thanks. Erza was staring down at her lap deep in thought and Makarov was looking at Gray skeptically, arms crossed..

"Hmmmm…" the Master mused. "Well I have no clue what happened, the only possible thing I can think of is that something is either wrong with your magic or it possesses some kind of power that we don't know about yet. Either way, Gray, you are forbidden from using this magic on any of your guild mates, alright? In fact, I would prefer if you didn't use it at all unless absolutely necessary!"

Gray nodded his head in acquiescence. "Fine. I was going to ask Lucy and Levy if they could help me look into devil slaying magic."

The guild master jumped off the bed, nodding. "Splendid idea m'boy! You can also examine the texts in the Library of Sorcery. For now though, you should rest and heal up, looks like your fight did a number on you both." He walked to the door of the infirmary before turning around one more time. "And Wendy you should rest too, you've been doing intense work since the battle." Wendy jumped at hearing her name before nodding and heading out the door after the master.

Erza who had been sitting lost in thought the entire time finally looked up at Gray when they were the only ones left. Gray was staring at his hands in his lap, silent.

"Gray." Said mage looked up and met the gaze of Erza's steely dark brown eyes. He raised a questioning eyebrow. "When you're rested come find me, I will help you look for information on your magic" Suddenly she paled "..despite the awful memories I have at the Library of Sorcery…" She shuddered and stood up after Gray muttered a quick thanks, exiting through the door after the others.

Gray sat silently for a while, thinking about how his magic was apparently more dangerous than he thought. I really hope we can figure this out. I can't avenge my family and kill END with a power I don't even understand. He glanced at his hands and then at Natsu, before swinging his legs over the side of the bed to sit in the chair by Natsu's bed. He examined the fire dragon slayer's face.

"I hate you dumb flame brain, why'd you have to go and get actually hurt? I mean are you so weak you were taken down by a tiny cut on your shoulder? How pathetic." Gray's gaze softened and he hesitantly pressed his hand on Natsu's cheek, noting with surprise how soft his skin was, despite the fact he always got into fights and could grow dragon scales on his face.

"I'm sorry. I wish I knew what happened." The unconscious dragon slayer lay motionless. Gray got lost in thought watching him, until exhaustion took over and he began to drift off to sleep.