Here's something spooky for Halloween, also throwing my little twist for when Bakugou gets kidnapped. (it's just for this story)

:p

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Kay was nervous, but she got enough courage to go and talk to Bakugou. "K-katskui...I want to ask you something..." He looked down at her, seeing her blushing a bit. "Okay, what's up? We gotta hurry because I still got homework to finish," he said in a more gentle tone than he would with others. "Katskui...you've been there for me for so long, you're so sweet even when you try to act tough for everyone else, you light up my world, so please...will you go out with me...?" Bakugou seemed surprised,  before chuckling a bit. "Heh...thought I would've been the one to ask, but looks like you beat me." 

"Huh, you-"

"I like you too, dumbass." 

Kay hugged him tightly, crying happily. "I'm so happy you like me too! I thought you'd never say yes!" Bakugou chuckled before picking her up and kissing her cheek. "Of course, Kay, you're so precious to me." 

Timeskip

Kay and Bakugou have been dating for a few months, but Kay seemed a little off. Her love never faded, and grew every day, but she seemed annoyed anytime someone tried to talk to Bakugou. "Hey Bakubro, do you wanna-" 

"He has plans later." 

The two looked at her. "Uh...I was gonna ask if he wanted to help me study real quick..."

"Oh, heh my mistake. Just hurry up okay?" she said in a sweet, yet twisted way that gave both chills, she then went to her desk and was looking at a book. "Is she okay?" 

"I'm not sure...I'll talk to her later." 

After class, they were getting ready for summer, where they had to pack up. "Hey Kay, can we talk?"

"Of course my lovely darling!~ What's  up?"

"Um, what was with Shitty Hair? I mean I love hanging out, but you made it seem like his wanting to be around me was a problem. I've noticed it with a few others, are you okay?"

"Oh, uh...yeah I'm okay, just don't wanna lose you is all...heh..."

"Kay...You know I love you, okay? You, not Mina, not Uraraka, you. Please don't be insecure about losing me," Bakugou then pulled her into a hug, rubbing her back. Kay hugged him back, feeling happy. "Okay, I'll try not to be, I'm glad that you love me and no one else." 

Timeskip pt. 2

After a few nights of training, they got to do something fun. Class A walked into the forest, and class B had to scare them. It was going great until there were sightings of the League of villains. 
(it's been a while since I've seen the whole episode so Imma skip a bit, sorry)

Deku was beaten up badly, but he and his friends tried to keep Bakugou safe from the League of Villains. Kay was acting as his guard, she even got a rock and made it into a spear. But their efforts weren't enough, and the LOV got him, Deku and Kay were so close to getting him, but not fast enough. 

All those hurt were in the hospital, even Kay, but she only focused on one thing. "I couldn't save him...he's gone..." She was in tears, thinking that she didn't do good enough. "Hey, you okay Kay?" Koy asked, checking on his sister. "I'm fine. I'm still here, I didn't get snatched..." "Hey, it's okay, we're gonna get him back. Kiri and I have a plan, if you're feeling okay, you can come with alright?" Kay looked at him with tears in her eyes. "O...okay, just tell me when." 

After a while, Kirishima, Deku, Momo, Iida, Koy, and Kay were on a mission to get Bakugou back. They had disguised themselves as to not be recognized, and went on the hunt. After a while (again, kinda forgot .- .) they had found out where the LOV was, and were discussing their plan to get Bakugou back, when Kay decided to walk in. "Kay! What are you doing?! Its dangerous to just walk in!" Iida yelled, but she ignored him, throwing her wig on the ground. 

She made a weapon out of the ground below before busting the door open. The LOV looked at her, Bakugou's eyes widen. "K-kay, what are you doing?" he asked, not wanting her hurt. "Well aren't you rude, haven't-" Shigaraki started, but Kay interrupted by manipulating the wind and dirt to blind him. As he rubbed his eyes, she rushed in, Toga getting in the way to attack. "I remember y-" Kay didn't let her finish, and used her spear slice her torso knocking her down and stabbing her in the chest. Everyone in the room looked shocked, including Bakugou. Kay looked at the LOV with a crazed look. "You're next." she said, pointing at Dabi with her bloody spear. He held his hand up, making a blue flame appear in his hand. "You sure you wanna do that, doll?" Kay didn't answer, she just took a water bottle out of her pocket, and used the water to wrap around the spear, going in for the attack. 

Dabi had burned her a little, but Kay didn't let that stop her from slicing his hand with the spear, water staying around it. After she cut his hand, she stabbed him right in the throat, pinning him to the wall. She left the spear there and grabbed a dagger in her back pocket, looking at Twice, who was afraid, then brave, then angry, and started to attack, but Kay cut his mask, freaking him out. She grinned, and stabbed him in the back a few times, blood getting on her face. The purple mist guy want to get Shigaraki, but she threw her dagger at him when he didn't see and got him in the side, going and moving the dagger up his body, pulling it out and causing him to collapse. 

She stood over Shigaraki. "What kind of hero are you...heroes don't kill..." 

"Maybe you should think twice about kidnapping the love of my life..." she used wind to control his hand, moving it to his own face, making him kill himself. "Glad I wore gloves," she said, putting the dagger in Toga's hand, then releasing Bakugou. "Are you okay? They didn't hurt you did they?" she asked, her personality changing to her regular self. 

"Kay...you...you just...-" "Shh, it's okay, no needs to know okay? We say they attacked themselves," she told him, hugging him. He was hesitant, but slowly hugged her back, and the two left. 

Timeskip pt 3

After the incident, and All Might fighting All for One, they were moved into the dorms, the teachers getting the okay from the parents. Once they were moved in, things seemed fine. Kay seemed a little more twisted, however, being more aggressive with her classmates when it came to Bakugou. Any joke or remark, she'd go off on them, protecting him from small things that didn't need protection from. Bakugou wanted to tell her to stop, but then he'd remember what she did. 

Even when class B picked on him, she didn't have it. "Look at this, it's the guy that had to get saved by a girl!" Monoma would tease, but Kay then went to him, grabbing the collar of his shirt. "Yeah. And that same girl can bury you with no one finding out. So leave my love alone, or you'll never be found." She threatened, letting him go. 

No one messed with her or Bakugou, and those who did besides the warnings, were never found...

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I tried, though I'm open to some yandere rp if you wanna throw your own twist in, hope you enjoyed!