The Demon's Concubine

Chapter 1

Natsu and Happy sat at the edge of the highest balcony of the castle. It seemed to be the only place the two could get some peace. No guards causing trouble, no servants asking for assistance, no subjects he had to impress. Peace.

He spent most of his free time like this; sitting on the balcony and catching up with Happy. It seemed as though in the 300 years he'd been king, he'd been seeing less and less of his best friend. At least he actually got to see Happy every now and again, since the creature was an official member of his court. His friends and family of the fairy and dragon kingdoms, on the other hand, he hasn't been able to meet up with or even call in years.

Natsu let out a long sigh. His life before he became king was so much more enjoyable. He missed going on adventures, traveling, getting into fights and just being himself. Here, he had to put up a strict, cold façade to not show any weaknesses. When he'd gone to royal etiquette and training courses, he hadn't paid much attention. He'd always assumed if he ever had to become a king, he'd just take over his father's kingdom, the Fire Dragons. 

What he hadn't expected was for his older brother, Zeref, to ask for him to take over his kingdom in Tartaros during his 100th birthday party. 

Natsu would've said no if it wasn't for the thousands of guests that had been anticipating Natsu's answer, some even celebrating for Natsu before he even made his decision. He knew if he told his brother that he only accepted due to the pressure, Zeref would've went back on his deal, but Natsu also didn't want to let him down. Zeref had just established the kingdom of Alvarez, and the year before that he'd just gotten married to Mavis Vermillion, the queen of the Fairy Kingdom. Zeref had a lot on his hands, and Natsu knew Mavis and Zeref wanted to have kids someday, but couldn't if their load was too full. Natsu wanted to help his family out, even if it meant being king of a kingdom he couldn't care less about.

Natsu wasn't sure what he had expected after his coronation. Tartaros was the kingdom of demons, and Natsu felt pretty qualified since he was a demon himself, the most powerful demon known to man, even. He'll never forget the serious talk Zeref had given him, telling him that now that he was king, he'd have to cut down on all the wild habits he had. "Cut down" meant get rid of completely, something Natsu had to learn the hard way.

The people of his court were insane. They were all so… serious. They acted as if the world was against them, and that they had to be on guard all the time. He hated their constant use of formalities, Natsu had gotten reprimanded so many times just for talking in slang. When they did let loose and have fun, it just felt so wrong. It was as if they were all laughing because they had to, and they were usually laughing at someone's misfortune. 

Not all of them were bad, though. Natsu found a friend in one of his top guards, Silver. Silver was the father of Natsu's close friend Gray, so he'd felt really comfortable around him. He'd given Natsu a lot of advice when he first entered Tartaros, since Silver had experience being the "new guy" from when he'd first went to Tartaros from the mortal realm.

Natsu was lucky to have gotten to take Happy with him when he became king, Happy and Silver being the only people he could actually call friends here. He was sure not all demons were as freaky as the ones in his court, but he'd never get the chance to find out since it was "unprecedented" for him to communicate with "common folk."

He let out a long sigh. He'd been doing this for 300 years, and he'd likely be doing it for many more. Zeref and Mavis were having their first child soon, but that didn't guarantee that the kid would even want to take over Tartaros, especially since they had the options of Alvarez or the Fairies. 

"What's wrong?" Happy asked as he crawled onto Natsu's lap.

"Nothin. Just tired."

"Are you feeling lonely again?" The exceed's tail wagged when he saw Natsu's irritated expression. Since he'd become king, it became clear he was unhappy with his life. Zeref and his father Igneel had assumed Natsu was homesick, which sparked the conversation of Natsu making his own "home" here at the castle. Igneel had sent suitor after suitor, hoping his son would fall in love and have children. 

Zeref did end up explaining that having a spouse whilst ruling Tartaros was risky. It'd be viewed as a weakness, which was only a serious issue due to Tartaros having the most enemies of the all the empires. This was why Zeref had wanted to let go of Tartaros once he got married, too.

Natsu had hoped this meant the two would lay off on trying to set him up with someone, but this only lowered their standards. They started sending suitors based on their looks and magical abilities. He couldn't get married, but that didn't mean he couldn't have a concubine or two. Or twenty… at this point Natsu was sure they were sending him so many women just so he'd finally have a kid, which seemed like such an absurd decision at this point in his life. 

Happy had taken to teasing Natsu everytime he rejected a woman. He'd call him picky, indecisive, boring, and now lonely, since Igneel and Zeref seemed to have given up on their mission to find Natsu a baby mama.

"Not lonely, Happy. Just tired." The demon king muttered. Happy really couldn't give him a break. 

"You wouldn't be so lonely if you had a girlfriend~"

Natsu decided to ignore his companion, simply scoffing and turning his head away from his teasing gaze. 

His eyes landed on the castle garden, or rather, something inside of it. Whatever it was had a golden glow to it, and upon further inspection, Natsu could make out blonde hair. 

"What…?" Natsu was cut off by the sound of running footsteps coming near the balcony door.

"Your Highness! There's a trespasser in the garden! You must come at once!"

The king sighed, dismissing the frantic guard. Whoever decided to trespass in the castle of Tartaros had a death wish for sure. He wasn't worried about it as he took his time getting to the gardens, Happy flying at his side.

When he stepped outside, it looked like a war had been called. Almost all of the guards were standing at attention, and his top guards, The 9 Demon Gates, were all surrounding who Natsu assumed to be the trespasser. 

"I believe it's an angel, my lord." Kyouka addressed as she poked at the person's body. Natsu bit back a groan; the angels were always on his ass. It made sense because the Angel Kingdom and the Demon Kingdom had been at odds since the beginning of their creation, but the demons hadn't initiated any trouble with them since Natsu had became king, you'd think they'd appreciate that.

"Please, can anyone tell me where I am?" A soft, strained voice asked. Now that he had walked upon them, Natsu could see that the intruder was an injured woman. He held a hand upwards, silently ordering the guards to stand back.

"Where have you come here from?" He couldn't even recognize his own voice, it came out much more intimidating than he'd usually allow it to. 

"I-I don't...remember," the blonde woman shook her head a couple of times, as if it'd help her remember something, "Where am I?" 

"Definitely an angel," Natsu heard Jackal mumble, "Look at how glowy she is." 

Happy stepped over to the woman, his tail swaying as he laid his paws on one of her thighs. 

"You don't know where you're from? Do you remember your name?" 

She rubbed at her eyes before staring at nothing in particular as she whispered, "Lucy." 

Kyouka placed a hand on her king's shoulder, whispering, "She's likely a spy from the angels. We should not let her walk freely." 

"Why are… Why is there so many people… Please, where am I?" The blonde pleaded as she finally met Natsu's eyes, and the demon found himself freezing up at her gaze. 

She looked so helpless, Natsu had never felt this amount of empathy before. He kneeled down to be at her level, clearing his throat.

"You are in Tartaros. You've gotten into the castle's gardens. That means you're trespassing. Do you know what happens when you trespass?" Lucy seemed to grow more shocked as Natsu continued. When she didn't answer, Natsu stood, ordering Mard Geer to bring her in for questioning. Whatever her business was here, Natsu knew she was dangerous. No one had ever come that close to breaking Natsu's façade, not even Happy, and he didn't even know this chick!

As he ordered all the guards to go back to their posts, he couldn't take his eyes away from Lucy as she struggled to stand and follow Mard Geer. She couldn't keep her eyes off him, either, and she gave him that helpless stare as she made her way into the castle. 

Natsu had to fight the urge to follow after her.

"Who the hell is she?"