Author's Note: Welcome back everyone! Thank you once again to everyone that left me nice reviews or followed or favourited the story, I'm very pleased with how much attention it's getting, and it isn't even halfway done. Nevertheless, I hope you guys enjoyed the last chapter, it was kind of difficult to write and it's probably my least favourite chapter so far. I'm working on another fic in conjunction with this one, so updates might be a day or two later than usual, but I guess that's the price of writing two stories at once (I'll link it for you guys when I post the first chapter, I think it needs a lot of polishing up before its readable, it's a NaLi fic btw). Enjoy the chapter, I took my time and it's probably one of my favourite chapters I've written!

Chapter 4: The Mark that Binds Us

Yukino sat at a table with Gray and Erza, twiddling her thumbs and looking worried. It had been 3 days since their return from the beach, and Sting had recovered enough that he was able to go back to Saber, albeit little grudgingly, but Yukino figured she didn't have to worried about getting kidnapped any time soon. That wasn't what worried her, though. It had also been 3 days since she had seen her boyfriend, Natsu. Every time she came around his house to see if he was home sick or something, he wasn't there, but she noticed his furniture was ruined and claw marks riddled the walls and wooden table through his window.

"Is Natsu-sama OK?!" she would ask her fellow guildmates, and they would all go quiet and tell her that Natsu got like this sometimes and he probably went off on his own to be alone for a while.

"Why would he do such a thing without telling me?" she asked, looking over at Gray and Erza, who looked at eachother quickly, exchanging uncomfortable glances.

"Well, you see, Yukino..." Erza began, but she was interrupted when Cana stumbled over, very drunk and put her hand on Yukino's shoulder and said very bluntly,

"Dragon Slayers get really horny now and then, Yukino, he probably went off to the forest to stop himself from taking your innocence by force."

"Cana!" Gray and Erza exclaimed, irritated at her lack of a filter for such information.

Going red in the face, she tried to form a reply but couldn't, the embarrassment was preventing her from speaking. Is that why he left without telling me anything? she thought to herself. But Natsu-sama would never do something like that to me...he loves me! I'm sure if I go talk to him, then I can get him under control.

Standing up, Yukino asked,

"Do any of you know where Natsu-sama went in the forest?"

"Yukino, that is a really bad idea, trust me. You do not mess with a Dragon Slayer in heat, unless you don't fear for losing your life." Gray responded.

"How bad can it be?" she asked, causing Erza to stand up and clear her throat, saying,

"A few times a year, seemingly at random intervals, Dragon Slayers give in to their instinctual desire to find a mate and reproduce. Not only do they lose their restraint around the opposite sex, their power increases significantly. Normally, Dragon Slayers are stuck in Dragon Force for the remainder of the week long mating period, but Natsu, who has unlocked Primal Dragon Force, will be stuck in that for a week. If he was dangerous before, he's a lethal threat to anything around him with that much pent up power and saw what he did to Sting, Yukino. Nobody can stop him, not even I or the Master, so he takes the liberty of removing himself for a week at his own will to be on his own so he doesn't hurt any of the women in the guild. Last year, he almost got a hold of Lucy but the whole guild had to fight him in order to subdue him, and even then, Gray nearly got his head cut off."

"It really is terrifying, Yukino, for your own safety I don't think you should go, you don't know what he might do to you." Gray added, shuddering at the memory of Natsu nearly killing him when he was trying to restrain him.

"Isn't there a way to calm him down?!" she asked, trying to find a solution for her boyfriend's suffering.

"Not unless you want him to mate with you, whether it's by force or not." Cana replied, sipping on her barrel of ale.

"Well, I have to help him somehow, I can't sit around and let him suffer!" she shouted.

"Trust me, you'll be the only one suffering if he gets a hold of you, Yukino. Natsu has been doing this for years, and he's no worse for wear when he returns. Just leave him be, and you'll have your boyfriend back in no time." Cana replied. "Unless...you want to be with him, Yukino?" she said with a smirk.

"I-I-uh, I mean...I couldn't..." she stuttered, all the blood rushing to her face.

"Cana! She's only 18!" Erza shot back.

"They're both of age, and it's not unnatural to be attracted to Natsu, Erza. I remember you tried to go after him one year-" she began, but Erza cut her off with a demonic glare,

"DO NOT MENTION THAT." she said, seething with anger.

"What about Gajeel-san and Wendy-san, then?" Yukino asked.

"Gajeel always goes up to the mountains when he begins to feel his urges acting up, and Wendy is too young to be affected anyways. Laxus is never around, and I'm sure Sting and Rogue have a plan just like Natsu and Gajeel." Erza replied.

I completely forgot about Sting-san, he's a Dragon Slayer too. Will he...come after me? she thought. She shuddered at the idea of Sting ambushing her and...she didn't even want to think about it. Natsu-sama would protect me. She was convinced about that much.

"I think I'm just...going to go for a walk then. Excuse me." Yukino said, standing up and leaving the table and walking off towards the guild doors.

"Be careful!" they called back as she walked out the door and set off towards the trail that led into the forest. It's my duty to help you when you're in pain, Natsu-sama, whatever the price is. Even though she never really gave it much thought, she wouldn't want to give her innocence to anybody but Natsu. Whatever happens...happens. Walking down the trail that lead through the forest, she began to notice the obvious signs that Natsu had been there: trees knocked down, long claw marks down their trunks and the potent smell of ash.

Continuing down the path, she followed the remains of trees until they led her to a small cave. It wasn't very deep, but she could see a small flame flickering inside of it, and figured that was where he was. Upon setting her foot inside the cave and hearing her shoes make noise against the cave floor, the fire immediately put itself out. What she heard next were sounds of someone sniffing the air, followed by a low and guttural growling sound. A bit unnerved, she responded in a nervous tone,

"...Natsu-sama? It's me, Yukino."

"Get...away." responded the very low, almost demonic voice of her boyfriend. She knew that he sounded like this in Primal Dragon Force, but she would be lying if she said it wasn't scary or frightening.

"Natsu-sama, I know why you're all alone out here, but I came because I want to help you." she responded in a sweet and calming voice.

"I...don't...want to hurt you...can't control...myself. Run...now." he said, in a tone that sounded like he was trying very hard to restrain himself. Taking another step forward, she heard him snarl and shout,

"NO! Leave!"

She knew that he was only saying that to keep him from pouncing on her, but she still felt sad that she wasn't able to help him.

"Natsu-sama..." she began, taking one step at a time, very slowly edging her way towards him. "I came here because...I want you to mate with me."

"...What did you say?" he asked, sounding much less restrained, but more curious.

"I want to be your mate, Natsu-sama. I want to be yours and only yours, forever. So please..." she said, outstretching her arms to the darkness in front of her,

"Take me."

That was all the encouragement that Natsu needed, as he practically lept from the shadows, scooping her up in his arms and running off through the forests at inhuman speed. The speed he was running at made her dizzy, the surrounding area looking like one large blur as he ran at speeds that made her hair whip behind her in the wind. After a good five minutes straight of running, they reached a clearing in the forest, just at the edge of the mountain. The clearing was wide open, but it felt strangely secluded, like nobody had been there in years.

"Dragons always return to their place of birth when they choose their mate, Yukino. This is where I was raised, by my father, Igneel." he said in his deep but now calm and content voice.

"Are you not frightened of me?" he asked, looking down on her, a sad expression on his face that was coated in shiny red scales, and his curvy horns that adorned the top of his head.

"Of course not, silly," she began, putting her hand on his face.

"I've never been so in love with anyone else in my entire life. No matter what form you take, you'll always be Natsu-sama to me, no scales or horns or even tail will change that. There's nothing more I would like than to be your mate for life, Natsu-sama, but will you have me?" she asked.

"Of course, Yukino, but are you sure you want to go through with this? Once I begin, I won't be able to restrain myself, no matter what happens." he said, gazing deeply into her big brown eyes.

"Please, enough talking, Natsu-sama. I'm...ready." she said quietly.

His scales fluctuating with a red glow, his canine teeth sharpened and elongated as he bent down and bit into the soft flesh of her neck. She screamed in pain at being bit with such force, but he immediately began to lick her wound, the saliva from his tongue acting as medicine and closing her wound, leaving only two teeth marks and... something else that Yukino would soon come to find out.

"Now for the fun part." he said with a snicker, taking his new mate over to the middle of the clearing where she kept quiet, blushing profusely.

Hours later at the guild

Gray sat at a bench by himself, rocking back and forth as Erza paced the guild hall. Yukino had not returned from her "walk" yet, and they were beginning to fear the worst.

"You don't think she..." Gray began.

"No, of course not..." Erza replied.

Silence.

"ERZA, I THINK THAT YUKINO WENT AFTER NATSU AND HE LOST CONTROL AND HE RA-" Gray screamed, before being hit over the head by Erza as she screamed back,

"DO NOT THINK SUCH THOUGHTS, GRAY, I'M SURE SHE IS COMPLETELY FINE."

"But she's been gone for hours!" Gray shouted back.

"Well...maybe she just stopped to get some groceries on the way home." Erza replied, her eye twitching.

"Why would Yukino need gro-" he began, but was interrupted by Erza's idealism again.

"Yes, that's it Gray! She just stopped for groceries. I'm sure she will be back any minute, unscathed by- NATSUUU!" she shouted, spotting Natsu, who was still in his Primal Dragon Force, carrying Yukino in his arms, her eyes closed. He carried her over to the two, his tail wagging like a happy dog as he caressed her cheek with his scaly hand.

Drawing her sword, she screamed,

"NATSU, WHAT HAVE YOU DONE? YOU KILLED HER!"

Making a "shhh" sign with his finger over his lips, he pointed at Yukino and mouthed "asleep." Still fuming, she angrily motioned for him to come over, and before he did, he motioned to Lisanna, who was watching, to come assist him, and instructed Lisanna to take Yukino and lay her down on a bed in the infirmary and assured her that she was not injured at all.

"Natsu, what did you do to her?!" she questioned angrily.

"Relax, Erza, she's not hurt in the slightest, but it is a very long story, so come sit with me and I will explain." he said calmly, motioning for his two friends to sit next to him. Erza and Gray reluctantly took a seat next to their scaly friend, as his tail idly thumped against the guild's wooden floor.

"Well, where to begin?" he asked, looking over at Erza.

"I don't know...where you took her innocence maybe!?" Erza shouted, stabbing her sword into the table. Gray about jumped a foot in the air where as Natsu didn't even blink.

"Well, first off, I didn't rape her, if that's what you're getting at. She came to me of her own will, and I gave her numerous opportunities to leave. Besides, taking her innocence wasn't my objective, it was mating Erza, and I was succesful." he said nonchalantly.

"DO YOU HAVE A DEATH WISH, NATSU!?" she shouted, slamming her hands on the table and Requipping a dagger into her hand and holding it at his throat.

"Go ahead, Erza. It's going to take a lot more to kill me than that." he said with a smug smile.

She didn't say anything, knowing very well herself that in Natsu's current form, there was very little she could do to hurt him, so threatening him with a dagger probably seemed pretty comical to him. Un-Requipping her dagger, she sat back down and crossed her arms.

"Well, as I was saying before, I did more than take Yukino's innocence. I mated with her, as all Dragon Slayers do with their significant other. Now that I've marked her, she's my mate for life." he said with his boyish smile.

"Wh-What?! What do you mean "marked her?" Erza asked, horrified.

"I bit her neck." he said nonchalantly.

"What's so significant about that?" Gray asked.

"Well, a lot of things, Gray. Dragons don't get married like humans, so when a dragon finds a mate, it marks the female's neck, claiming her as his own for the rest of their lives. When a dragon takes a mate, there is no going back, and the two are joined for life. The marking I gave Yu-chan is a lot more meaningful than just teeth marks, it's ancient magic that can only be used by Dragon Slayers that shares the attributes of a dragon with another human, something that is no longer possible without mating, since all of the real dragons are gone, so legitimate Dragon Slayer magic, or First Generation Dragon Slayer Magic, cannot be achieved.

Since I am of the First Generation, I shared my magic with Yu-chan when we mated, replacing her Celestial Spirit magic with my Fire Dragon Slaying magic. So, Gray, what do you think that makes Yukino?" he asked.

"She's...a Fire Dragon Slayer now?!" he asked in disbelief, to which Natsu nodded.

"Is-is such a thing even possible?" Erza asked, surprised at what he was telling her.

Nodding his head, he continued,

"That's the same for all Dragon Slayers. When Dragon Slayers mark their mates, they share their attributes with the person, also sharing their powers if they aren't already a Dragon Slayer. In addition to that, Yu-chan and I will most likely live twice as long as any of you, since we now share one life force." he said.

"Is that all?" Erza asked.

"Nope. The reason Yukino is asleep right now is due to the biological changes occuring in her body as a result of becoming a Dragon Slayer. When she wakes up, which should be some time today, she'll probably be a lot stronger physically and magically. Dragon Slayers have a larger magic capacity than normal mages, so she'll be able to last much longer in combat, as well as possessing the enhanced sight, hearing, smell, and the sixth sense that Dragon Slayers seem to possess exclusively." Natsu said.

"Sixth sense?" Gray and Erza asked in unison.

"Aye. It's a mostly unknown sense Dragon Slayers possess that allows them to communicate telepathically with others of their kind, a sort of link between all of the people that use our magic. It's also likely she's subject to a change in appearance, but I'm not so sure about that." he explained.

"How would her magic change her appearance? And if Dragon Slayers do have a 'sixth sense', why don't you, Gajeel, Wendy and Laxus ever use it?" Gray asked.

"Well it could be anything to an extra inch in height to a change in hair colour. All of this is written in a book from the guild library, by the way. There's probably lots of details that I'm leaving out, but Dragon Slayer magic drastically changes a human being. The sixth sense thing, as far as telepathic communication, only works between mates, Gray, but I can feel other Dragon Slayers' presences, if that's what you mean. Oh, one more thing that's really important." he added.

"What's that, Natsu?" Erza asked.

"When dragons take a mate, they're EXTREMELY protective of them. If they feel they're in danger or their mate is threatened, they're very likely to kill the person instigating it. This also applies to members of the opposite sex trying to separate the two, like, if Lucy tried to kiss me or something. If Yu-chan saw that happen, she might attack Lucy. Anyways, be wary of people that might try to separate the two, because when a dragon is separated from it's mate, it never ends well." he said very seriously.

"Good to know..." they said in unison, both imagining Yukino beating Lucy to a pulp after kissing Natsu.

"Anyways, is there anything else you guys needed to know? I'm not hiding anything from you." he said.

"Does that mean Yukino is on the same level as you, power wise?" Gray asked.

"I don't know yet, but I would assume that she's close to me. Our magic and magical power is now identical, but our technique probably varies. Who knows, she might be more powerful than me." he said modestly.

"Can she use Primal Dragon Force too, then?!" Gray asked.

"I guess so, I can't wait to see her kick your ass, Gray!" he said, laughing at his own joke.

"As if! I'd totally destro-" he began, but was interrupted when Natsu shot him a glare that could literally kill him, saying in a demonic voice,

"Or you would what, Gray?" he said, threatening the person who had dared speak of harming his new mate.

Gulping loudly, he responded,

"N-nothing, Natsu, I'd let her beat me up..." he whimpered.

"Great! Nice to know you're being a good sport for once, Gray." he said, instantly reverting to his cheerful attitude.

"Hey, Natsu, weren't you supposed to return to normal by now? Why are you still in that form?" Erza asked, eyeing his scaly body.

"What-oh! I guess you're right, Erza, I hardly even noticed. Strange, it feels...really natural to be like this. I kind of like it." he said, looking down at his scaly hands.

"Natsu..." Erza began, a tone of worry present in her voice, "maybe give that form a break, alright? You shouldn't spend too much time like that, it can't be good for you."

"Yeah...yeah, you're right, Erza." he said, returning to normal, his heavy scales hitting the ground with a clunk as they fell off of his body.

For a second there, it seemed like he didn't want to return to normal, Erza thought. Is it really good for him to be using that form so much in succession? Erza had paid attention to Natsu's words during the fight with Sting, and she thought of what he had said to Sting about Primal Dragon Force:

"The only other person to have used this form was Acnologia, not that he's around to tell you about it. That's the reason I try to restrict myself from using this form unless I feel I need to, the more that I use it brings me closer to becoming a real dragon."

Worried for her friend, she suggested that they all go check on Yukino in the infirmary. Natsu immediately agreed, leading the group behind him to go check on his mate. Entering the infirmary, he thanked Lisanna who had been sitting at her bedside, and sat down next to the sleeping young woman. Natsu wasn't lying when he said there was a slight change in appearance, Erza could tell that Yukino's fangs were growing in and she noticed her hair had grown an astounding length in such a short time, reaching all the way down her back.

Natsu, putting his hand on her cheek, smiled as he eyed the young woman and kissed her on the forehead as he said that they should give her some space. Closing the door behind him, he smiled and closed the door, eager to spend the next day with his girlfriend.

Some time later

Yukino awoke with a start, panting heavily and feeling very dizzy. She didn't remember much about what had happened to her before she passed out, besides Natsu marking her and their... other activities. Looking around the room, she looked like she was in a pseudo-hospital, which she guessed was the guild infirmary. It was nighttime, the moon's light shining in through the window and leaving an odd glow that illuminated parts of the room. She felt strange, like her own body was foreign to her. She moved her tongue around in her mouth, and felt...fangs?

Unsure if she was imagining them, she touched them with her fingers, and sure enough, just like Natsu, she had sharp and pointy canine teeth. Examining her new features, she felt around her whole body, noticing her much lengthier hair and seemingly more developed muscles. Feeling around where Natsu had marked her, she felt a strange warm and tingling sensation that, as she felt further, reached all the way around her neck and was snaking it's way down her left arm. Slightly unnerved at the sensation, she got to her feet and stumbled over to the bathroom to examine herself in the mirror.

What she saw surprised her greatly, but not nearly as unnerving as she had imagined. Wrapping around her neck and making it's way down her arm was a beautiful pattern of black flames that stemmed from her neck where Natsu had bit her. Also noticing her new super-long hair, which she would think wouldn't look good on her, actually looked very beautiful and felt smooth as silk. True to her feelings, she had put on a good amount of muscle compared to before, and she also picked up on a difference in her ears: they were pointier and smaller than before, giving her an elfish appearance. They weren't apparently for show either, because she could now hear sounds that she never heard before: the wind blowing outside, even though it was not windy at all, as well as the ambient background noise of the light buzzing in the background.

Is all of this happening because Natsu-sama mated with me? she asked herself, and to her surprise, she recieved an answer.

"Yu-chan? Is that you?" she heard a familiar voice ask.

"Natsu-sama?" she thought.

"Wow, this is so cool! Say, Yu-chan, how are you feeling?" Natsu asked her mentally.

"My hair is really long, and I have pointy teeth and super hearing and I feel a lot stronger for some reason. What's happening to me, Natsu-sama?" she asked him.

"Well, I don't know how to really tell you, Yu-chan, but when we mated, you took on the attributes of a dragon, just as I do. All of the changes happening to you, the teeth, hearing, the longer hair and sudden strength... it's because you're a Fire Dragon Slayer, like me." he responded.

"What?! You mean...I can use your magic now?!" she asked.

"Yeah, give it a try, Yu-chan. Imagine fire in the palm of your hand, trust me, it should feel second nature to you." he answered.

Taking a minute to compose herself, she held out her palm and did as he instructed, and she felt the warm blaze of a small fire burst from her hand.

"Wow, this is amazing! Thank you so much, Natsu-sama!" she said.

"Don't mention it," he said, laughing to himself, "but I'm afraid to tell you that you can't use Celestial Spirit magic anymore, Yu-chan. I'm sorry."

"Natsu-sama...don't feel bad. Even though I'll miss my spirits, I'll give my keys to Lucy-san. It's OK, really." she replied.

"I'm...so glad to hear." he said, sighing in her head, "But, Yu-chan, do you feel alright? You were asleep for a long time."

"I feel really good, actually. I'm getting used to my new body already. Where are you, by the way, Natsu-sama?" she asked.

"I'm at home, Yu-chan. I'll be waiting for you, I have a surprise." he said, ceasing their mental conversation.

Wondering what he had wanted to show her, she walked out of the infirmary and out into the nearly-deserted guild hall. She figured it must be very late at night, since the only people (or person, rather) that was there was Mirajane, who was idly washing dishes with a bored look on her face. When she noticed Yukino leaving the infirmary, her head shot up and she called out to her,

"Yukino! Are you finally feeling alright?!" she called out to her from across the guild hall.

Walking over to greet her, Mira gasped at her new hairstyle that had appeared as a result of her transformation, saying,

"Wow, Yukino, your new hair is beautiful! How did you get it to grow that fast!?" she asked, dying to know her secret.

"Eh, well...it's kind of a long story, Mira-san. Do you mind if I leave now, Natsu-sama told me that he had to show me something back at his house." she replied.

"Oh, you can go whenever you wish, Yukino. But, how did you know that Natsu wanted you home?" she asked.

"Call it a Dragon Slayer's intuition." she said nonchalantly, waving at Mira and running out the guild doors and into the night, leaving Mira confused and curious at her interesting comment.

Yukino had never experienced the outdoors like she could now, she could hear all of the little sounds she never noticed before, and the smells of the open world were all so new to her. She marvelled at her new senses as she walked towards her mate's home, taking in all of the little details and making careful observations. Her pointy ears pricked up at the sounds of owls hooting, crickets chirping and the low howl of the wind. It was like being born anew, experiencing these sensations for the first time.

As she reached the outside of Natsu's house, she noticed the small sign that Natsu had outside the front of his house which normally read "Natsu's Home", but now read "Natsu and Yukino's home". She thought the gesture was very sweet, and she knocked on the door, as Natsu came and opened it for her.

"Oi, Yu-chan! Wow, your new hair is so pretty!" he exclaimed, earning a blush from the silver-haired Dragon Slayer.

"Thank you, Natsu-sama, but what is it that you wanted to show me so badly?" she asked.

"Ah, well...come take a look for yourself." he replied, taking her hand and leading her out his back door and into his backyard, where a large furnace that was sculpted to look like a dragon's mouth sat in the middle of his yard. The fire inside of it's mouth burned brightly, lighting up the dark surrounding area with an ominous orange glow.

"Natsu-sama, what is that?" she asked, confused as to whether this was her gift or not.

"Ah, but you'll see in a moment, Yu-chan." he responded slyly, walking over to the dragon's mouth and reaching inside of it, pulling out a small object and closing it in his palm, and then hiding his hand behind his back. Turning back around to face Yukino, he walked up to her and looked into her eyes for a moment, as if trying to find words.

"Yukino, when you came to see me earlier today, it was one of the scariest moments in my life. Not because I'm scared of you, but because I was scared of hurting you, scared of doing something I would regret for the rest of my life. Not too long ago, you joined our guild, and that made me happy to know that you had such a loving family and a guild hall that you could call home. I told you a long time ago that I wasn't sure what made you different from the other girls in the guild, but I've finally realised what that is." he said, gazing deeply into her eyes.

"Yukino, I will always fight for you, cry with you, and I would die for you. No woman has ever made me feel like that, not Lucy, not Lisanna and not Erza. What I found in you that I couldn't in anyone else was a person that I wanted to spend the rest of my life with. A person that if I woke up and I wasn't next to, it would feel like a nightmare. Someone that I can nurture, and protect, and they can do the same for me. Someone that should I lose, would make me half of a whole, a shell of the person I used to be. Words can barely describe what I feel for you, Yukino, you're one of a kind, the only medicine to cure my sadness and the key to my happiness. Every day with you is a day in Heaven, and I don't want to go back down to Earth again, not ever. That's why I want you, and only you, Yukino." he said.

After that, he opened his palm and placed the ring made of gold, forged in the flames of a dragon and embedded with a piece of his soul on her finger, saying,

"Will you marry me, Yukino?"

Is this a dream? she thought, Is this really happening?

"If this is a dream, Natsu said in her mind, "then I hope it's one that I never awake from. I love you, Yukino."

Jumping into his arms, tears streaming down her face, she shouted,

"Yes, oh my God, yes, Natsu-sama! I thought you would never ask..."

"Yukino, I'm so happy that I'll finally be able to call you my wife. This is the happiest day of my life." he said, running his fingers through her long silver hair.

"Me too, Natsu-sama. I love you so much, I don't know what to say. This really is a dream come true." she replied through tears of happiness.

Somewhere far away...

"Natsu." Igneel said, smiling to himself. "You've found yourself a wonderful mate, haven't you? I'm so proud."