As I flew towards Fionna's house, I tried to plan out what I was going to say.
Ok, "Fionna, weird question, but..." no, no too awkward.
"Hey Fi, stupid question I know, but..." no, because if she actually is then it'll sound like I think she's stupid...
"Hi Fi, sorry, but I just had to make sure, you're not, like..." ugh I don't know, maybe something like that.

I reached her treehouse and knocked on the door. When Fionna opened it, I realized how nervous I actually was, and whatever plan I had flew out the window.

"Hey Marshall what's u-"
"Are you afraid of me?" I blurted

Fionna stared at me for a moment.
"What? Marshall Lee what are you talking about?"

I took a deep breath, regaining my composure.
"That night, when I used some of my demon powers on Flame Prince, did I scare you? And be honest with me."

Fionna was quiet for a moment, thinking. She looked at Marshall Lee. At first glance, anyone would just see some troublemaking kid. But, looking into his eyes, Fionna saw those thousand years of experience. Marshall Lee was wiser than anyone gave him credit for. But she also saw power, strength, and cunning. It was true, Marshall Lee was dangerous, but Fionna was not the type to back down in the face of danger.

"I suppose...Yes, I am. But not in in the way you're thinking."

Marshall tilted his head in confusion.
"What do you mean?"

"Well, there's two kinds of fear," she explained, "The first is what most people think of when they think of fear. The panicking, screaming, paralyzed out of fright kind of fear. Then, there's a respectful kind of fear. You don't scare me. When you were in you demon form, I didn't feel like I was going to scream or panic. But, I do realize that you are powerful, and that if for some reason I ever were to go against you, I wouldn't stand a chance. I have enough respect of your power that I know not to be stupid or reckless concerning it."

"So, like, you know that I'd never hurt you, right? You get that?"
"Of course!"

I sighed a sigh of relief. See Marshall? You got yourself all worried about nothing.

Now that that issue was out of the way, I had my confidence back. Well, almost.

I chuckled.
"Wow, Fi. I finally use some of my real power and I still can't scare you. You're no fun," I say with a smirk. Fionna giggled.
"Come on, I'm the bravest adventuress in all of Aaa! Besides, you're just Marshall Lee."
"I'm just Marshall Lee? C'mon Fi I'm much more than that. I'm the Vampire King! I'm the demon prince of the Nightosphere! And..." I placed myself right in front of Fionna, looking directly into her eyes, "I'm pretty sexy," I said with a wink. Fionna's face turned beet red.
"M-Marshall..."
I smirked.
"Flustered, are we? Could it be now that you've seen a fraction of my true power you can no longer resist my charms?"

Fionna pushed me away, her face still bright red.
"You're crazy."
"Maybe."
She smiled.
"Dude come on I have to go to sleep. Stop messing with my head and junk."
"Alright, alright," I sighed, floating toward the window. "Ok if I come pester you tomorrow?"
She rolled her eyes.
"Whatever."
"Don't use that tone with me, young lady," I teased. "After all, you're speaking to a king."
"Psh. Some king"

Fionna watched as Marshall Lee flew off towards his house. Ha! Some king, she thought to herself as she climbed up into her room and snuggled into her bed. Whenever Fionna thought of kings, she thought of grace, dignity, royalty, and formality. Marshall Lee didn't show any of those things. Except maybe grace. The way he casually floated just off the ground. Even when he set his feet down he walked with a smooth, confident gait. That confidence could be mistaken for arrogance, but only sometimes. He was rather full of himself, and he admitted it. Openly.

Though his arrogance didn't make him a bad dude. To Fionna, Marshall Lee had always been one of her best bros. They enjoyed a lot of the same things; games, playing pranks, and music (Marshall liked to play it and Fionna liked to listen, which worked out pretty well). He was always considerate of her feelings, never blaming it on her "overreacting" or being "that time of the month." Even if he didn't always get it he considered them valid. And no matter how embarrassed or annoyed she got there was a part deep down where she actually enjoyed it when he teased her. Not to mention he was extremely attractive.

Wait, what?

Fionna shook her head. He's messing with your head, Fi she thought, unknowingly referring to herself using his nickname for her. She buried herself in her blankets, curling up to go to sleep. Just don't think about it. It's not like he even thinks of you that way anyways, so just forget it.