Rated MA for some strongly suggestive and sexual content. This is my first fanfiction, so feedback would be strongly appreciated. I'll continue the story if you guys like it!
It was 7 in the morning, and Fionna the adventuress let out a soft yawn as she stretched her arms out in bed. Cake was still asleep, of course, and Fionna's hunger was growing quickly. She sat up in her bed and swung her legs off the side of the bed. Yawning again, she stood up and walked into the kitchen. Her eyes pondered until focusing in on her favorite cereal. She poured herself a bowl, and began eating. Shortly after she sat down, she watched as a silhouette appeared outside her window. She knew who it was. "Fionna, open the window would you?" Marshall Lee called from outside. Fionna slid open the window to the kitchen and let Marshall hover in. "Hey, Fi," He said casually. Fionna raised an eyebrow. "Were you wanting something?" She asked in curiosity. Marshall not only wanted something, he wanted someone. He wanted Fionna. Now that she was an adult, he just began to realize how incredibly hot she is. "Yeah, wanna come to my place today?" He asked. "Sure, Marshall, just let me get ready first," She laughed. He watched as she ran up the stairs to the bathroom where she would shower and change out of her pajamas. Marshall sighed at the thought of her gorgeous body underneath the warm water in the shower, right upstairs. He quickly shook the thought from his mind, and grabbed an apple off the counter. He sucked the colour out of the fruit, then licked his lips. He could hear the water running upstairs, and was getting more impatient. He wanted to spend the night with her, he wanted to play music with her, watch movies with her, and fall asleep right beside her. But most of all, he wanted to make love to her. Badly. Minutes later, Fionna started down the stairs in skinny jeans and one of Marshall's band tees he left at her house once. He was staring at her the whole time, which caused her cheeks to turn bright pink. Before she could say anything, he grabbed her by the hand and was out the window with her, heading to his house. When they arrived, he gently put her down on the couch. He picked up his bass, and started playing a tune. Fionna nodded her head slightly, and started humming along. She looked so beautiful, and her voice was so pure and perfect. "Oh glob Marshall, not now..." He thought to himself. His cheeks turned bright red and he put down the guitar, stopping the music instantly. "What's wrong?" Fionna asked. He bit his lip and sat down awkwardly. That's when Fionna noticed the erection forming in his pants. She started blushing, and tried to ignore it out of embarrassment. She had always had a huge crush on him, ever since she met him... and this might just be her best chance at getting something more than just a friendship with Marshall. He was so mysterious, so dangerous, and so freaking sexy. She knew that he wouldn't be able to resist her, so she hopped up onto his lap and startled him with a deep and passionate kiss. His reaction as she pulled away amused her. "Fionna wh-" He was surprised, confused to say the least, especially since this was coming from Fionna, the "innocent" adventuress. Before she could lean in and kiss him again, he had reached his head down and started kissing along her neck. He could feel the goosebumps forming under his cold lips, and continued down her neck. Hesitantly, he pulled her shirt over her head and exposed himself to her chest. He was getting harder and harder each second, and he almost couldn't take it when she pulled off his shirt and started tracing her fingers along his abs. "Make love to me, Marshall." She whispered into his ear sweetly. All of a sudden, he had her in his arms and was carrying her to his bed. He threw her down, and began to unbuckle his belt and pull down his jeans. She sat up, and began groping him through his boxers. He let out a soft, muffled moan, and unclasped her bra, flinging it onto the floor. He then worked his way down her thighs and pulled off her jeans and panties. He was pleased with what he saw. His tongue worked itself in slow, hard circles around her clit and it didn't take long before she came. Sitting up, she pulled off his briefs and grabbed his erection in her hands. She didn't quite know what to do with it then, but Marshall didn't mind. He guided her head down onto his hard on, and brought her to a steady pace. He threw his head back in pleasure. "Oh glob," he mumbled. He pushed her back down onto the bed and quickly pushed himself inside of her. He heard her hymen break, but wasn't all that surprised. She was, after all, still innocent little Fionna. She closed her eyes shut in pain and pleasure, and gripped the bed sheets underneath her tightly. Marshall sped up his pace, and formed a quick and hard rhythm inside her. "Jeez, Fionna I'm..." She looked up at him with a smirk amongst her face. It turned him on. Within seconds, he slammed himself deep into her and released his fluids, letting out a deep and loud moan. He didn't take the time to realize what he was doing, as he sunk his teeth deeply into her neck, still moaning. Fionna gasped. "OH MY GLOB, MARSHALL! What the junk are you doing?!" She screamed. She quickly pulled herself away from him, and sat there just staring into his eyes. "Please tell me you didn't..." she said, angrily. Marshall pulled at his hair stressfully, tears almost forming in his eyes. "Fionna I - I'm so sorry I just... I was so into it that I didn't realize and I, I couldn't help myself..." Fionna looked down at the two swollen marks on her neck, and ran her fingers over them. "What's going to happen to me, Marshall?" She asked nervously.