Warning: Yandere Nath is gonna go cray cray this chapter so I'll make sure to warn you before we get to the crazy part. There's more of the story after that though so make sure not to leave the chapter before reading it! The crazy part's really short, anyway so it doesn't matter. It's kind of pointless, to be honest.
(The song kind of goes with the crazy part. Like, it doesn't relate, I just think they're a good combination.)

The dress

The hair

Your point of view
I was so excited for the homecoming dance! I had finally found the perfect dress yesterday with help from Marinette and planned on wearing my hair in a mermaid braid. It took forever to perfect the hair, but it was worth it. I was ready to walk out the door when my mum saw me. "(Y/n)!" She said, and I could tell she was crying. "You look beautiful! Nath will love it!"

I was taken aback by those last few words. "How'd you know I was going with Nath?"

"Your father isn't known for his secret-keeping abilities," Mum said.

"Sadly, you're not wrong. Well, I guess I'll get going. My friends are waiting."

"And your boyfriend!" She added happily. I sighed and walked out the door.

"(Y/n)! Girl you look great!" Alya said. She had gotten one of her friends who had their driver's license to drive us to the dance.

"Didn't I tell you it was the right dress?" Marinette said as I hopped in.

     "Yeah, whatever."

Third person point of view
Where is she? He wondered. Surely she wouldn't ditch me. Perhaps she just took longer than expected to get ready. Yes, of course. He was getting anxious, waiting for his (Y/n). He sat at his table alone, silently waiting, bathed in shadow. Occasionally people would make small talk with him but he would drive them away before long.

     He finally got tired of the waiting and he got something to drink. He admired the punch in his cup. Red, the color of passion, and blood. This made him think, if anyone tried to take his (Y/n) then this would be their blood in his cup. He would love to drink the blood of anyone who messed with him.

     He sat back down at his table, his patience slowly being replaced with anger. How dare she leave him there alone! He needed her. She could not, under any circumstances, leave him. As he thought this, she walked into the dance. He ran over to her, fuming. "Why were you so late?!" He yelled. "You had me worried that you weren't coming!"

"I wouldn't ditch you, Nath," (Y/n) said in her gentle way. She laid her head on his chest.

"THE PARTY HAS ARRIVED, MY PEOPLES!!!" Alya yelled out. Marinette chuckled.

"Well I'll leave you lovebirds alone. I've got a child to take care of," Marinette said, referring to Alya. She walked off with a smile.

"Wanna dance?" (Y/n) asked her boyfriend. He shook his head.

"I just want to be with you for now," he told her. He picked her up bridal style and sat in his chair with her in his lap.

"N-Nath?" she asked, blushing wildly.

"Yes, my (Y/n)?" He said.

"People are probably going to see me sitting in your lap."

He smirked. "Good. I want them to see this, that way they know you're mine." He kissed her roughly, not caring to be gentle like he used to. He used to be so sweet and innocent, but something had changed since he fell in love with (Y/n). He was completely immersed in her. He had to have her with him, he had to kiss her, he had to make sure everyone knew that she belonged to him and no one else.

She was his, he was hers, and that was that, as he put it.

"Nath," she whispered, "please, we're in public.."

He grinned. "I love it when you beg," he whispered.

"Nath, shouldn't we dance or something?" She tried to change the subject.

"If that is your wish, my (Y/n)," he said, "then it is my command." She stood up, and he took her hand. They danced together for the longest time until she said, "You know you've been acting different lately."

"What do you mean?" He asked her.

"You seem much more confident in yourself and...you're a tad...possessive of me, it seems. Is everything okay?"

"Oh, everything is perfect..." he trailed off. "Well, almost, but things can't be completely perfect, not yet."

"Why not?" She asked.

"Because I can't marry you," he said simply.

"Nathanaël, we're fifteen and you're thinking about marriage. Are you insane?!"

"Why yes I am, my sweet (Y/n)," he replied with nonchalance. "Have you only just noticed?"

Sawyer watched Nathanaël and (Y/n) dance with pure envy for the (h/c) girl. She was supposed to be with Nath, not her. He was supposed to be hers, she felt it in her heart. Apparently he didn't feel the same. She wanted to cry; she was at the homecoming dance all alone, without even friends to be with. She truly was alone in the world, just like she'd always known.

No one would ever love her.

She wasn't good enough for something like that, she knew that, but sometimes she pretended she was and that someday she would find her true match. She was Annabeth, and would someday find her Percy. Someday. And today was that day. Nath would love her; she would make sure of it. When (Y/n) broke away from Nath to go to the restroom, Sawyer took her opportunity. She went behind Nath and hugged him. He knocked her to the ground. "Stay away," he whispered in a deadly tone. "You must be either really stupid or really persistent. Either way, I can't stand you. Go away before I do something I won't regret." She squeaked and scurried off.

     She had made up her mind. She would find him after the dance and talk to him, whisk him off somewhere special where they could be alone. Without that diddly darn (Y/n).

     (Y/n) ran back to give Nath a hug. "I'm back!~" she sang. He chuckled a bit and held her close to him. He kissed the top of her head and smiled. "Well, shall we return to the dance floor?" She suggested.

     He shook his head. "I'm tired, I think I'll just sit down."

     "Oh, okay," she said. She sat down on his lap and he smirked.

     "You don't seem too worried about what others think now, huh?" Nath chuckled.

      She put her arms around his neck. "Not really, no. And Sawyer's watching so I've gotta show her who's boss."

     "She tried to hug me earlier. I might've threatened to kill her without exactly saying it."

     (Y/n) stood up. "You what? Nath, she might be annoying and insanely persistent, but don't ever threaten to kill a person! What's happened to you?"

     He wrapped his arms around her waist. "I'm obsessed, that's what."

     "With what?"

     "Why, with you of course."

     Sawyer wanted to cry as she saw Nath's girlfriend sitting in his lap like it was nothing. They were so effortlessly cute and perfect and Sawyer despised it. But suddenly, (Y/n) stood up and started yelling at Nath. Sawyer tried to sneak closer over to hear what they were saying.

     "...might be annoying and insanely persistent, but don't ever threaten to kill a person! What's happened to you?" Sawyer heard (Y/n) say. She couldn't believe that this girl was standing up for who Sawyer could only assume to be herself (because Nath probably didn't have dozens of crazy fangirls he threatened to kill).

     Nath wrapped his arms around (Y/n)'s waist and Sawyer flinched. "I'm obsessed, that's what," Nath told (Y/n).

     "With what?" (Y/n) asked.

      "Why, with you of course," he said, which made Sawyer die inside.

     (Y/n)'s expression softened. "Ah, Nath you cinnamon roll. That's precious." He snickered. "What is it?" She asked.

     "Don't you understand? It's not precious. I'd kill for you, I'd die for you, I need you. I'm nothing without you, you have me at your disposal, and I can't let anything get in our way. I'd do anything for you," Nath said. "And Sawyer is in our way. She needs to go." Sawyer gasped a little, then tried to cover it up and scurry away.

     "If you'll excuse me, my sweet, precious (Y/n)," Nath said, "I have business to attend to. I'll be right back."

      She cocked an eyebrow, but didn't protest. He went right to Sawyer, and pulled her outside the school by her hair. He smirked; this was it, he finally got to kill this girl. "N-Nath?" Sawyer whimpered.

     "Shh," he cooed, putting a finger to her lips. "Don't worry."

     "Are you going to kill me?" She whispered.

     He laughed a bit as he tied her up with the rope he had in his little top hat. He finally tied a cloth over her mouth so she couldn't scream and draw attention. "Perhaps you're not as stupid as I thought," he told her.

     He pulled a long dagger out of his boot. "My (Y/n) isn't the only one who carries weapons with her."

     Sawyer tried to speak, but it was muffled.

     "I assume you're asking why I'm killing you," he said. "The answer is simple. You're a pest. You're in the way of me and my (Y/n). Therefore, I must exterminate you. After all," he grinned devilishly, "that's the only way to get rid of a pest."

YEAH THIS IS THAT GOREY DEATH SCENE I MENTIONED WHERE NATH GETS KIND OF CRAZY. IT'S ALSO REALLY SHORT AND POINTLESS AND AWFUL BUT OH WELL.

     Nath slit the girl's throat first, then he completely removed the head from the body, which took a lot of work. Luckily, when it came to such things he was quick. He smiled as her blood spilled everywhere. He didn't bother to clean it up, rather he just let it taint the green grass a lovely crimson. He admired the deep copper red of blood, but he admired the taste of blood even more. He collected some of her blood in his glass until it was filled all the way.

     He sipped the blood and smiled. This was the most fun he could ever have besides being with his (Y/n). It was a hell of a feeling to kill a person, especially one that was complicating things for you. He set his glass down and picked up Sawyer's severed head. He stuck his fingers in her eye sockets and pulled out her eyes. He squeezed the eyes between his fingers until they popped and he smiled.

      He cut off each of her fingernails, then he took off the fingers, and did the same to her toes. He took out her voicebox and threw it behind him. He cut out her heart and cut it apart as well. He found pleasure in this, although none of it was necessary. He cut off her hands, and her feet, and kept chopping her up until all he had left was a pile of blood and severed body parts. He had removed all the internal organs and had left all of it there, separated from the other parts they used to be joined to, yet still with them.

     He found a good spot to hide the parts where no one would find them (for a while, at least): Sawyer's own gym locker. Since those typically didn't smell good anyway, it wouldn't be very suspicious for a little bit. Long enough for him to escape with his (Y/n).

THE SCENE OF POINTLESS GORE IS OVER NOW.

     Once he finished his work, which had only taken about twenty minutes, he picked up his glass and took another gulp. He walked back inside the dance, not a drop of blood on his suit. The only things stained were his hands. He went to the bathroom to wash up when someone walked in and saw the blood.

    "What happened?" The guy asked Nath.

     "Ah, I spilled some of my punch, you see," Nath said casually.

     "Ooh, that's no fun," the guy said.

     "No, no it's not," Nath simply stated.

     Nath had been gone for twenty minutes and (Y/n) was starting to wonder about him. Finally, he was back.

     "What 'business' did you have to attend to that took so long?" (Y/n) asked innocently, oblivious to what had happened.

     "I killed her," he whispered in his (Y/n)'s ear.

I'm not going to lie. I had soooo much fun writing this!!!!! I started writing it as soon as I got the previous chapter published because I simply loved this idea although I doubt any of you guys do. So sorry if I've ruined this lighthearted x Reader for you, lovelies.