Okay, this first chapter isn't super exciting, but it'll get better! ( I hope xD )

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Marshall Lee and Fionna had been together almost the whole day. Cake had a date withLord Monichromicorn, so Fionna had called Marshall to come hang out. They were just now walking back to Marshall's house and it was getting dark.

"Hey, Marsh," Fionna started slowly.

"Yeah?"

"Will you, um, hold my hand? I'm kinda scared..."

Marshall seemed to get upset with Fionna when she said this. "Now why the flip would you, Fionna, the greatest adventurer in the land of Aaa, be scared of the dark?"

"Never mind," sighed Fionna.

Marshall immediately regretted being so rude. He would have loved to hold Fionna's hand. He was just confused about why she would want him to hold her hand. She, of all people, wouldn't be scared of the woods. There must've been another reason.
A few minutes later, Marshall reached down and grabbed Fionna's hand. She responded by looking at him and smiling. He could see the deep blush in her cheeks.
They were nearing Marshall's house, and he felt a sharp tug on his arm. Pretty soon, he was rolling down a grassy hill with Fionna. They reached the bottom, both giggling and dizzy, when Fionna moved so she was sitting on Marshall's stomach, pinning him down.

"Hey, Fi, get off!" Marshall whined, hiding the fact that he didn't mind her on top of him.

"No way, Marshie! You'll just have to stay here all night!" Fionna sent herself into a fit of giggles, and this was when Marshall noticed something- with her legs spread, he had a perfect view of Fionna's red panties.
'Is she doing this on purpose?' he thought.

"I won't mind staying here as long as you're sitting right there!"

This had Fionna giggling again, and Marshall Lee saw this as a perfect escape plan. He slid out from under her, carrying her bridal style back onto the path.
They didn't say a word, except for Fionna's random giggling fits, until they arrived at Marshall's house.

"I should get you home, babe, Cake'll get worried."

"First of all, Marshie," calling him his despised nickname, "don't call me 'babe'. And second, I need to ask you a favor."

"Whatever you need, Fionna."

"Well, then, whatever I need, you say? Well I need some chocolate!"

"Ha-ha, super funny. What do you need?"

"Okay. Can I sleep over?"

Marshall started laughing. Fionna pouted at him laughing at her.
"Babe, if that's it, sleep away! But, me being the responsible one here, you should probably call Cake and tell her. You said you'd hang with her all day tomorrow, since it IS your birthday."

"Yay, thank you, Marshie!"
Fionna was so excited that she gave Marshall a little kiss. And, even though it was just a peck on the cheek, could she see him blush!

Inside Marshall's House...

"Hey, Cake! Guess what? Marshall said I could sleepover at his house!" Fionna gushed into the phone.

"Now whose idea was this?" came Cake's skeptical tone.

"Mine!"

"You really do like him don't you?"

"No," yelled Fionna, angrily "I don't like Marsh like that. We're just bros! Hmph."

"Alright, whatevs." replied Cake, not wanting to start something.

"I'll see you tomorrow, love you, bye!"

"Love you, sista!"

Marshall had been waiting to hear Cake's disapproval of his and Fionna's little sleepover. But instead, Fionna came back, grinning about how fun it would be!
"Hey, babe, calm down! Maybe you need to go to bed."

"No way, you patoot!"

'Fionna is gorgeous. Look at her brown eyes, and her perfect figure.'
He noticed how she hadn't minded when he called her 'babe'. Marshall couldn't help but love Fionna. And he has no idea how much she loves him back. Poor thing.

"Hey, Fi, do you have pajamas?" Marshall questioned.

"Hold on!" Fionna said while running in the direction of Marshall's room.

She emerged wearing just one of Marshall's old plaid shirts, barely concealing her panties underneath.
"Woah." Marshall couldn't help himself from staring. She looked amazing.

"You don't mind, do you?"

"No, no, no... I mean of course not... I mean, you know, I mean you look great in it! So, yeah, you should wear it!" Marshall had trouble speaking in front of this girl. Good, old experienced Marshall, at a loss for words because of one girl? Shocking, even to himself.

"Hey, let's get to sleep, you gotta wake up tomorrow!"

This made Fionna giggle.
Marshall grabbed Fionna by the waist and dragged her into his room.
"Here, I'll get the bed ready for you." Marshall needed this night to be perfect, so that Fionna would want to sleep over again. He had to be super gentleman-like and stuff.
He got all the bedding ready and lay Fionna down, then tucked her in and gave her a little peck on the cheek. But Fionna seemed to have different plans. She pulled his head back down and gave him a long kiss. When their lips parted, Marshall knew he wanted more. Fionna knew it, too.
But Marshall pulled himself away from the bedside to set up the air mattress he had in his closet.

"Marshall..."

"Fionna?"

"I'm cold." both Fionna and Marshall Lee frowned at the statement.

"Well, I could get you another blanket or-" started Marshall.

"Marsh, just get in the bed with me."
Marshall had no objections to that.
Marshall Lee pulled back the blanket, noticing that the top three buttons of the shirt Fionna borrowed from him were undone, revealing just a bit of perfect cleavage. He felt awkward being that close to her, so he stayed his distance. But Fionna surprised him by pulling him in closer and kissing him.

"Um-" Marshall started.

"Shushers!" Fionna interrupted cutely as she pressed her lips to his.

Fionna pulled away to breathe, and Marshall took the chance to speak.
"You know, for someone who's never had her first kiss before this, you kiss pretty good."
All Fionna did was blush.

"Fi, I'm about to eat the pink right out of your cheeks. It looks amazing." Marshall smirked at her.

"Oh, hush. You wouldn't do that to me. Would you?"

"Hm, I don't know. Depends what kind of mood I'm in." he laughed.
Fionna kissed him on the tip of his nose lightly. "Goodnight, Marsh."

"'Night, babe."

Fionna let herself lean into his chest, and Marshall wrapped his arms around her, protecting her from invisible evils.

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So, did you like it so far? It's my first fanfic ever, so give me some pointers and stuff ^.^
Thanks!