Um, so here is new story, a one-shot and well this isn't Beta read and probably won't be so you'll have to ignore any wrong spellings.

I don't know what else to say, kind of a cliche story but whatever, Enjoy!

I know that the ending is kind of doubtful and wouldn't happen in real life but please bear with it, it's a fiction after all. I based Lucys decision here on her altruistic personality. Forgive me for that, it was my youthful naivety.

Primal Instincts.

All animals in the world have the desire to mate and reproduce, some more than others. Unfortunately dragons belong to the category with a stronger need because of their numbers drastically dropping over the years.

So they had no choice and used ancient magic that forces them to hunt for someone compatible to breed with that has the highest chance of passing down the strongest genes.

During the mating season the dragon is not aware of anything happening around them, or their choices. Their instincts make all the choices for them. Even if it's some that they don't want to make.

Sadly for Natsu, who was clueless about all of this never had a chance to prepare himself.
For him it was a normal day, he trained a little, went fishing with Happy and spent some time in the guild, then it all went black and the next thing he knew he woke up with a headache and naked, with an equally naked and unconscious Lucy a few feet away.

He immediately became alarmed and ran to her side. "Lucy, wake up. What happened?" Natsu shook her but she didn't respond, he shook her again but she still didn't wake up.

It was at that moment that Natsu really smelt the air, it was heavy and laced with something that only confused him.

He then noticed the mark on her neck, a small bright red flame stood out, marking her for the whole world to see and Natsu realized in that moment that he had claimed her and the second he realized that the memories from the night before came rushing back.

Natsu had been spending time with everyone at the guild just hanging out and enjoying the time.

It had been around midnight when Natsu had started to feel strange, his mind had been clouded almost as if a fog had entered disrupting everything and he couldn't think straight anymore.

He had barely been able to get out of the guild before his body had taken over, moving on it's own completely disregarding him, it was as if his own body had betrayed him.

His instincts had taken over, Natsu knew it because it had happened before, it usually happened when his life was in danger so they kicked in and saved him, that was why he wasn't as alarmed as he should've been. Although it did make him wonder what they thought was out there that threatened him.

Natsu had moved in the middle of the night quietly and unseen, he had found himself on top of the clock tower that stood proudly in the middle of town. He looked down at the view and smirked, let the hunt begin.

He released his magic and it had immediately sprung into action and started searching the town, it moved like a mist not missing any crook or cranny. Natsu stood by patiently and waited, he knew his magic would get a reaction soon enough.

Just as he predicted he didn't have to wait long, the magic working fast to fulfill it's purpose, he felt the reaction as it spiked, alerting him of it's find and position.

By now Natsu had lost all control of his body, he had barely been aware of what had been going on.

His body moved stealthily and carefully, he didn't need to be seen by anybody right now. His magic was still alerting him of it's position as he ran, as Natsu turned a corner he recognized himself to be on the street that Lucy lived in.

He stopped outside of Lucy's apartment and realized that his magic had chosen her, he grinned at that fact. He couldn't have thought of anyone better to be his mate.

He didn't want to waste any time so he jumped up and entered the small apartment, Lucy had stopped locking it since they all entered through here anyway, which only made it easier for him right now.

He noticed that Lucy was sleeping and it gave him the few moments he needed to set everything up. The first thing he did was emit a shield around the premise so that no one would notice. After he was sure that it worked he moved over to the sleeping Lucy and climbed on top of her.

She was a heavy sleeper and didn't wake up, Natsu smirked at her defenselessness a little happy that she didn't feel threatened enough to wake up.

He brought his head down to her neck and took a long sniff, she really smelled divine, how he could've missed it before he had no idea.

He looked at her content and sleeping face before he let out a small chuckle, he bit her and injected a bit of magic as he did. The bite had woken up Lucy with a scream so he had clamped her mouth with his hand to stop it, not that it mattered no one would hear her as long as the shield was up.

He had felt the blood enter his mouth and it only caused him to bite harder to get more of it, it was delicious. Eventually he had felt Lucy squirm and try to throw him of which only angered him and it made him growl to try and make her submit.

The feral growl made Lucy stop but she started crying instead and when the smell of her tears had entered the room Natsu stopped biting to look at her, she had her eyes shut hard and tears were flowing down her cheeks. He removed his hand from her mouth and she took a big breath while moving away from him.

The act had angered him and he growled again. She brought her hand up to her neck and felt the blood, and when they locked eyes he saw how her body relaxed a little.

"Natsu? What's going on? Why did you bite me?" Lucy was confused and a little angry. She had started moving away from him so that she could go and assess the bite.

"Don't." Was the only thing he was able to say, he was already restraining himself and her moving away from him didn't help. She was inviting him for a hunt, except she didn't know it.

"Don't what? I don't have time for this, my freaking neck is bleeding!" She had screamed the last part, finally waking up and understanding the situation. Her best friend had bitten her enough to draw blood.

The moment Lucy had raised her voice it had caused Natsu's last restraint to disappear, she had challenged him for the role of alpha and he couldn't stay sane anymore.

Lucy noticed the moment the feral look in Natsu's eyes appeared and immediately felt fear, this wasn't the Natsu she knew and that thought alone encouraged her to escape. The bite mark had been completely forgotten and she turned to run out of the door.

Natsu knew right away what her plan was and he pounced on her and pinned to the floor with her hands above her head. He growled and moved in. Lucy whimpered truly frightened and she looked away.

She tried to use her magic but noticed that she wasn't able to and it scared her more then Natsu, "What did you do to my magic?!" She screamed at him.

"I didn't do anything, I simply made sure that we wouldn't be disturbed by anyone tonight." Natsu growled in her ear a little angry that she had once again raised her voice. He moved in closer and kissed her.

Lucy refused to return the kiss so she simply pressed her lips together into a thin line. Natsu noticed this and growled again, but she didn't budge so he bit her lip, the pain had made her whimper and she had opened her mouth by accident and it was at that moment that Natsu shoved his tongue in and successfully deepened the kiss.

Lucy still tried to resist but every time she did Natsu would tighten the grip on her hands until it hurt so she had no other choice but to cooperate. She had no idea what was going on with Natsu and quite frankly she didn't want to find out either, she just wanted to escape because she knew that he wasn't sane at the moment.

Natsu felt when Lucy had started to return the kiss and it pleased him so he started kissing more ferociously. Lucy tried to keep up but Natsu hadn't given her any time to breathe so she turned away to try and catch her breath, however, he wouldn't allow it and grabbed her chin so that he could continue.

When Natsu sensed that Lucy was completely out of air he backed up, saliva connecting them and he grinned at the flushed look Lucy had. She was trying to finally catch her breath so she didn't notice that Natsu had started to undress her.

Natsu had let go of Lucy hands and she had finally relaxed, thinking that the whole thing was over. She tensed up the moment she felt Natsu's hands on her thighs and his head in between her legs. She tried to move it away by grabbing his hair and pushing but it didn't help, it was like trying to move a rock.

He spread her legs so that he could have better access and licked her clit and she shuddered not used to the feeling. She leaned her body against the door in an attempt to move away from him but it only gave him a better approach.

Natsu smirked before he shoved his tongue inside her, Lucy gasped surprised because she had not expected that. He pumped his tongue in and out and it didn't take long for Lucy to cum.

Lucy panted and fell forward over Natsu, she bucked her hips unknowingly and Natsu groaned and shoved his tongue inside her as far as it would go. His teeth brushed her clit with each pump and Lucy came yet again.

She felt exhausted and panted heavily, Natsu took that moment in act to stand up and get undressed.

She looked up at him as he undressed, the moment gave her some clarity and she realized where this was going.

She knew that this wasn't Natsu but there was nothing she could do since he was stronger than her and it didn't help that he had sealed away her magic somehow.

So with this one moment she stood up quickly and ran to her bedroom to try and lock him out, the movement had surprised as well as angered Natsu and he growled at her but it only inflicted fear and gave her the motivation to run faster.

So Natsu immediately gave chase and followed her quickly, he forced the mark that he had placed earlier to react and it caused Lucy to lose all strength in her body. She tripped on the far end of the leather ottoman and fell over it.

"What did you do?!" Lucy screamed angrily, the fear had disappeared and now only the anger remained.

"Nothing that concerns you, all you need to know is that you should never do that again" Natsu leaned down and grabbed her legs, he had no plans on giving her strength back in case she tried to run away again.

He drove his tongue back inside Lucy's pussy and she tensed up, he didn't take notice of it and continued to lick her to try and get her to cum, she had been ready for him before but her little stunt forced him to repeat the action.

Since she had just came her pussy was overly sensitive so it didn't take long for her to reach her third orgasm. The fact that her body came so easily pleased Natsu and he smirked, it not only meant that the mark worked but also that her body was feeling comfortable with him.

This time Natsu didn't want to wait, he brought his cock closer to her pussy and coated himself with her juices by moving in between her thighs. Lucy felt every move and it froze her, she had thought he would stop.

"Natsu, wait. You don't need to do this." Lucy stuttered and tried to move away but her strength still hadn't returned so it looked like she was crawling.

Natsu noticed and brought his face closer to her ear while grabbing her throat, "I do, and this is going to happen, whatever you like it or not." He growled in her ear before he shoved her back down on the ottoman and penetrated her with one push. Her hymen broke immediately and she whimpered, a few drops of blood flowed out but it went unnoticed.

Natsu paused and groaned while Lucy tried to swallow her tears, he was big, too big for her and it hurt.

The feeling of her around him was too much and he couldn't get himself to wait for her to adjust anymore so he started moving at a fast and rhythmical pace and Lucy could do nothing else but allow him.

He kept on fucking her and increased his pace with each thrust, Lucy was having a hard time keeping up and it was even harder considering she didn't have any strength.

Natsu felt her trying to move and took it as a sign that she was trying to flee again so he collapsed his upper body onto her very hard, pinning her in place, he moved up the bench and then he rammed her, showing her that she isn't going anywhere. Lucy merely whimpered with the new force he was using.

The new pace made Natsu moan out of pleasure and it caused Lucy to cum hard, all over his legs and balls. She bucked under him, completely at his mercy now. She tried to move around but realized that he wouldn't allow it. Only mere seconds after he groaned loudly and Lucy's attention shot up.

She might've been new to sex but she knew that wasn't supposed to happen. She looked behind to where they were joined and saw to her horror that a knot had started to form at the end of Natsu's dick. She tried to make him stop and realize that it wasn't supposed to be like that but her plea fell on deaf ears.

The moment she understood that, she tried against her better knowledge to try and get away from his pounding cock, but Natsu would have none of that and growled loudly and started fucking her harder to widen her, it was then that Lucy realized that he was trying to force his knot inside her and started to struggle even more.

Natsu wasn't bothered by her tries and continued to pound into her and finally, after a few thrusts, he succeeded in getting his knot in so he hummed in satisfaction.

Lucy felt the air leave her lungs the moment it entered, she could feel it vibrate inside of her as his cock grew, spurting loads of pre-cum into her, practically every time he thrusted inside of her and she shuddered at the foreign warm feeling.

Natsu kept shooting huge wads of hot pre-cum at least every 30 seconds or so while fucking her, she could literally feel her pussy sloshing with all his sperm.

His knot was still expanding inside of her, now absolutely huge, plugging her completely. He didn't use it strictly as a method of plugging, he fucked her with it and Lucy felt it move inside of her as his hot pre-cum spurted inside of her every few moments.

Natsu began to take long, hard thrusts into her, stopping at times, holding off so he didn't come to soon but eventually he began grunting louder and louder, each thrust making Lucy's legs flail.

Then he did it, he braced himself and groaned, and Lucy felt the contents emptying themselves inside of her.

She screamed and flopped under him as he continued to thrust, his cock vibrating and jerking inside of her, the tops of her feet bouncing on the floor. He came for 6 minutes inside of her, his knot still fully inflated. The temperature of his cum was incredibly hot, almost unbearable and she could feel each and every spurt enter her.

Natsu growled loudly and brought his fangs to bite her again, this time he pushed all of his magic inside of her marking her as his. Lucy screamed at the pain and the heat, but could do nothing to stop him.

After he released her neck, it took another moment before Lucy finally felt his cock starting to shorten inside of her and she relaxed a little, Natsu straightened up and stood on his knees, Lucy realized then that he had put all of his body weight on her, making sure she couldn't get away from his pounding, but he didn't try to pull away yet and waited.

As his knot deflated, even with his cock still inside, his cum exploded from her and Lucy moaned against her will and bucked. She heard it pattering down on the hardwood floor and she felt it flowing down the front of the ottoman, rolling off the leather to create a puddle.

Lucy came a final time and felt her strength starting to return, but exhaustion replaced it as quickly as it came.

She started to slowly get up thinking it was finally over, but, Natsu had other plans, that's when she noticed his breathing had become ragged again.

He shoved her down, his cock stiffening inside of her. She felt him growl and froze, unable to believe that he could have any sperm left after the huge load he'd shot.

Natsu decided to take it slow this time as Lucy laid beneath him, she tried to get up a few times, but his body would tense up and shove her back down, she realized then that her pleasure didn't mean a thing to him, Natsu was going to take her until HE was satisfied.

He began thrusting hard again, grunting VERY loudly. As he rode her, his cock seemed to get even bigger, and she couldn't help but groan as his knot re-entered her. When she cried out, she heard him grunt even louder and his cock twitched hard, forcing her into yet another orgasm.

Lucy moaned and felt him shoving up on the bench further and further, then gasped when he climbed on top of her from behind, his legs now off the floor. His cock penetrated her even deeper and now she was completely pinned.

Natsu went into a frenzy, his breath gasping, his cock slamming into her forcing itself inside of her. Lucy's body slid up and down on the bench, her entire front eventually being covered in cum as he continued to pump on top of her for another 30 minutes, his cum sloshing inside of her and her cunt sealed shut by his knot.

Natsu started cumming for the second time and Lucy felt his hot spunk exploding from his jerking cock, his moans and gasps of pleasure were being heard through his chest, Lucy's cum covered face turned to the side and her body crushed beneath him. Her legs flailed on either side of his huge body as he filled her up again.

She shuddered under him, they were both covered in each others cum and when he finally softened enough to pull out, his cum came out with such force that it actually splashed on the floor as she laid on her stomach on the bench, her legs over the side, his cum pouring out.

He finally got off of her, his cum still streaming out and Lucy laid down there for a few minutes before she stood up shakily, she looked down at her normally flat stomach, now actually distended by his cum, it was the last thing she noticed before she fainted, exhausted by the whole ordeal.

Natsu caught her before she hit the floor, and took her in his arms so that he could have a look at the mating mark he had placed on her. He saw it starting to form on her neck, a flame replacing his bite mark and smiled happy that her body had accepted him. He gently kissed it before he put her down on the floor and then he backed up to watch her one last time, his mate, before he let the mind take over again.

Natsu held his head as the memories came rushing back making him relive it and tears started forming at how he had treated one of his best friends.

He picked Lucy up and cradled her in his arms and nuzzled her face while muttering apologizes. Lucy never responded and it only made Natsu cry harder at how rough it truly must've been for her if her body was too exhausted to wake up.

He tried to wake her up by shaking her or tapping her cheek but she was unresponsive so he opted on taking care of her body instead, because whatever he liked it or not she was now his mate and his to take care of.

So he carefully picked her up and carried her to the bathroom so that he could clean her up. He immediately put them both in the tub as soon as it had started to fill up, not caring about the temperature since he could just heat it.

Both of them laid there in each others arms, Natsu was doing his best to clean her body as carefully as he could and winced with every bruise or mark he found. He never meant for it to go this way, he had planned on disappearing during this time but it had come early, his birthday wasn't for a couple of months.

After he had dressed Lucy and put her on the bed he sat next to her holding her hand and waiting for her to wake up. Fortunately he didn't have to wait long, Lucy started to stir after a few moments and Natsu held his breath, afraid and ashamed at the same time for different reasons.

Lucy woke up slowly, her whole body screaming at her to not move a muscle with each move and she whimpered, but obeyed the wishes of her sore muscles. She felt the warmth that was surrounding her hand and knew that someone was holding it. She decided to ignore it and rest, whoever it was they could wait.

"Lucy?" Natsu asked quietly wondering why she wasn't saying anything, was she in too much pain that she wasn't able to? He nudged carefully, not wanting to touch her too much in case she hated him.

Lucy knew Natsu was beside her the moment she heard the voice calling out to her, but the memories she had frightened her far too much and it made her fear opening her eyes, but the moment she felt his nudging she knew that it was the usual Natsu beside her, so she slowly opened her eyes and turned her head to watch him.

By now Natsu was crying while watching her and that broke her heart so she smiled weakly at him to try and reassure him that she was fine, somewhat.

"Are you alright?" Lucy asked while squeezing his hand.

The question baffled Natsu and he started crying harder, Lucy tried to sit up and reassure him she was fine but the sole act of actually trying to sit up hurt and Natsu saw the pain her face so he immediately enveloped her in a hug and cried in her shoulder, Lucy allowed him too and tried to pat him to try and calm him but every time he succeeded in calming down he saw the mark on the shoulder that showed the world that she was his and regret filled him.

"Me? You're asking me if I'm alright? I should be asking you that, stupid" Natsu hugged her harder, angry at her for not caring about her own well being more, she should've just killed him or something so that it wouldn't have gotten that far.

"I'm fine, don't worry." Lucy patted him and leaned into him tiredly.

"Don't lie, I hurt you badly and I know it, you should've killed me Lucy. At least that way you would've been fine" Natsu angrily spat out. Lucy simply stayed quiet allowing him to vent out his anger, it wasn't until she heard him talk of his own death that she herself turned angry.

"Then what? I kill you and then? I'll be without my best friend and Fairy Tail will miss it's salamander, what good will that do? I knew you weren't being yourself Natsu, how could I not know? I'll never blame you or anyone for that matter for something that they do without them knowing it, so Natsu look at me. I forgive you, I do. Although if you ask me there's nothing to forgive." Lucy explained tiredly, she was exhausted and would much rather sleep but she knew that Natsu needed to her this.

"Stupid" was the only quiet response she got and she felt like hitting him for the insult, but that would actually require her to move and waste energy and it was too much trouble.

"We both know you would do the same" Lucy said after a while, she was falling asleep by now.

"That's different, you lost your virginity. I know how girls care for that, I've been listening to it since I was a kid." Natsu defended, once again annoyed at her for not seeing how wrong he had treated her.

"That's true, but I didn't lose it to just anyone, I lost it to you. Someone I care about and I can live with that Natsu, so forgive yourself because I already have" Lucy said before she fell asleep in his arms too tired to stay awake, and Natsu just continued to hold her not wanting to let her go, half because of the mating mark and half because he was afraid that if he did, something worse then what he did would happen to her. She was safe in his arms and that was the most important thing.

"Lucy, please don't fall asleep, I need to tell you something." Natsu whispered into her ear, trying to stop her from falling asleep. It barely worked but he noticed her eyes trying to stay open, and he took it as a sign that at least she was listening.

"What happened last night was something that we dragons call mating season. It makes us run on instincts to find the most suitable mate" Natsu explained softly, he saw Lucy nodding and continued.

"Yesterday, I chose you, that's why everything happened, well like it did." Natsu explained and unknowingly held her tighter. Lucy on the other hand noticed and it made her sober up a little from her sleep.

"What does that mean, for us?" She asked curiously, in her mind she had thought that they would return to normal, but this new information questioned that.

"In normal terms I guess it would mean… marriage." Natsu mumbled a little embarrassed about it.

"What?" This revelation had woken Lucy up wholly and she was staring at her friend with her mouth open wide. Natsu wished he could comfort her and tell her that everything was going to be okay, but it wasn't, they were bonded for life.

"What does it mean?" Lucy asked and tried to get up, she needed to wrap her head around this. Natsu reluctantly helped her, he would've much rather still have her in his arms.

"I told you, during this time we find the person most suited for us and mate, the mark on your neck is proof that we bonded for life" Natsu explained and he noticed how she reached for her neck.

"You mean from you biting me yesterday?" She asked and tried to trace the mark but she was following the pain so she wasn't sure if she got it correct. Natsu nodded at her question and looked down ashamed.

"I see, so it means that we'll be together forever huh?" Lucy asked with a sigh, this wasn't how she pictured life turning out. Natsu nodded again at her assumption.

"Anything else I need to know?" Lucy asked, she could feel herself getting tired again and she wanted to go to sleep and continue this after a good rest. Natsu didn't say anything but she noticed him biting his lip and looking away, it caused her to narrow her eyes at him.

"Out with it" She eventually demanded tired of his stalling. Natsu looked at her and fidgeted before sighing and giving up.

"Dragons are very territorial creatures, and well, I'm probably going to be very territorial of you from now on, and I know that sometimes it isn't going to make sense but I won't know any better" Natsu explained as he looked down at his hands. A moment of silence ensued and Natsu looked up at Lucy wondering why she hadn't said anything. She was busy with her own thought so she didn't even notice him observing her until she looked him in the eye.

"How territorial?" She finally asked curious as to where Natsu drew the line.

"I don't know, I guess it would be depend?" He offered not really sure himself, this was new to him, he wasn't exactly active when it came to love.

"Ok, let's take an example then. Gray." Lucy said and Natsu growled at the mention of his name.

"He has a habit of stripping in front of people down to his birthday suit, would you be fine with that?" Lucy asked curiously.

"No!" Natsu screamed in a growl and wrapped her body in an embrace, she wasn't allowed to look at other men, especially not naked men.

"Ok, so no interaction with naked men, got it." Lucy said with a laugh.

"How about conversations, you know as friends?" She then asked concerned that Natsu's instincts would stop her from having any male friends.

"Of course that's fine Lucy" Natsu said softly while the guilt started to return, he never meant for her whole life to change like this.

"Well, we'll handle each hurdle as they appear" Lucy eventually said to tired to continue this conversation right now, she really and desperately needed sleep. She had started to slowly drift to sleep.

"There is one more thing" Natsu said after a while, he felt the courage leaving him with every second. Lucy only hummed tiredly, she wasn't paying attention anymore but she humored him with sounds that made it seem like she was.

"You're pregnant"

"WHAT!?" Lucy screamed as she sat up in bed startled by the revelation. Natsu cringed at her high pitch but nevertheless nodded.

"Are you sure? Wait how do you even know?" Lucy rambled frantically.

"Dragons always creates life when they copulate during mating season… even once." Natsu explained and looked her dead in the eye to convey how serious he was. Lucy looked back at him for a few seconds before her hands flew up in the air in surrender.

"Oh God, I really didn't need this right now" Lucy mumbled to herself, if there was one thing she hadn't expected it was this.

"This is too much information, so other than us being married or mated or whatever you want call it, I'm also pregnant, great" She mumbled and brought her hand over her eyes. She didn't notice the wounded look Natsu had from her mumbling, but right now there were too many things swirling in her mind to take notice of anything else.

"Is it really that bad? That it's me?" Natsu asked after a while with wounded pride. The question made Lucy freeze and she looked at her friend.

"What? Of course not Natsu, If anything I'm glad that it's you and not some stranger" Lucy quickly said and gave him a hug, she felt him growl at the mention of another man, but didn't comment.

"I'm just overwhelmed about how fast this is going, and how it turned out. It's like everything was pushed on to me and now I have to handle everything with some missing information" Lucy explained the best he could, she wasn't even sure himself. Natsu nodded and accepted her words of comfort, he was in no position of judging her since he had forced everything on her after all.

"Now Natsu, tell me honestly, is there anything else I should know?" Lucy asked, it was clear that he wasn't going allow her to sleep before he had told her everything.

"No, not anything that I can think of right now" Natsu said with a smile happy that he told her everything.

"Ok, good, now please let me sleep" Lucy sighed and returned to her pillow happily, there were still allot of things she needed to figure out but right now her body needed sleep in order for her to process everything properly. She felt the bed dip as Natsu came and laid down beside her, he brought his hands around her in a protective way and relaxed.

"I'm so sorry, but I promise that I'll do everything in my power to make it up to you for the rest of our lives." Natsu whispered in her ear, thinking she was asleep. Lucy smiled as the words registered in her tired mind, even if everything had gone wrong and nothing had been planned, she knew that as long as it was Natsu it was going to work itself out somehow.