After posting a bit more detailed chapter, I realized I didn't have it in me to write that kind of stuff. Sorry guys! I've re-edited this chapter so hooopefully it's better this time around.
The sound of someone knocking at the front door caused Fionna to wake with a start. Hurriedly she clambered out of bed and pulled on a robe she had in her closet before rushing down stairs.
"Coming!" She shouted, padding across the living room floor. The visitor turned out to be Cake, who had brought some home made soup and other treats for her sister. The cat immediately sensed something different about Fionna, "Girl what happened to you?"
"Oh I just woke up! I couldn't sleep last night." She wasn't completely lying.
After a moment of eyeing her sister suspiciously, Cake entered the house and set the basket of food on the kitchen table. Fionna busied herself with making Cake a mug of catnip tea and a pot of coffee for herself.
She was still very sore from the previous night, but tried desperately to hide her discomfort from Cake. She didn't hold her stomach, and managed not to wince, but maybe it was the slightly strained tone in Fionna's voice that raised a particular question with Cake.
"So how're things with you and Marshall?" Cake asked as she daintily sipped from her mug of tea.
"Oh Glob.." Fionna thought. Steadying her voice she replied, "We're great! We went and visited Gumball last night. You should've seen Marshall's face when Bubba hugged him, it was priceless!"
"I bet it was girl!" Cake chuckled, then her face turned serious; It was almost as if a switch had been flipped.
"Where is Marshall by the way?" She asked, flicking her tail in what Fionna knew was agitation. She wasn't out of the woods yet with her sister.
"I'm right here Cake."
Marshall appeared out of thin air next to Cake, he was wearing his favorite black plaid pajama pants and gray tank top. He laughed in satisfaction when Cake nearly jumped out of her seat in surprise.
"Dang it boy! Ya gotta let me get used to you being fang-faced again."
"You never will Cake, just accept it." Marshall chuckled and floated on his back next to Fionna, he winked down at her and caused her cheeks to flare up in a blush as she remembered the previous night with him.
Cake eyed them for a moment, "...You two had sex didn't you?"
"Yep!" Marshall announced proudly.
"NO! NO we didn't!" Fionna yelped, but it was too late. Although Cake hadn't tried to claw Marshall's eyes out, she did sit there in shock for a moment. Fionna could only lay her head down on the table in horror and embarrassment.
Marshall continued to float casually in the air, hands behind his head and whistling a merry, light-hearted tune. Cake was still stunned, but Marshall finally spoke to her in hopes of easing her out of her shock, "If it makes you feel any better Cake, I love your sister more than life itself and I would never do anything to harm her. I also know, that you must have known this would happen sooner or later, am I right?"
Cake sighed, "Yeah, doesn't mean I have to like it though. She's my baby sister after all, and if she wasn't already an adult I would probably have to slice you to ribbons."
"Understandable." Marshall replied casually. Fionna looked over at him, still blushing furiously at the fact that Cake now knew about their nightly activities.
"I'm gonna get a shower..."
Both vampire and cat watched Fionna scurry out of the kitchen before they were left alone in each other's company. Cake had plenty more questions for Marshall, and he had more than enough time to answer all of them now that Fionna was out of the room.
"So do you plan on taking your relationship any further than... this?"
Marshall floated into the seat across from Cake, and sat with his elbows propped on the table, "If you must know, I did pick out a ring the last time I picked up her medicine in the Candy Kingdom."
Cake's eyes went wide.
"Really Cake? Is it that shocking that I want to marry your sister?"
"Well no but..."
"Good, because if I have your permission then I'd like to ask her in the near future. Think you can handle having me as a brother in law?" He grinned at her, and Cake couldn't help but laugh a bit. "I'm just a little concerned about the predicament you two are in..."
"What do you mean?" The moment the words left Marshall's mouth, he realized what Cake was referring to."
"She's human... You're not."
Marshall was silent for a moment, thinking of how he should carefully phrase the next words he would be speaking, "I won't turn Fionna unless she asks me to...is that what worries you?"
Cake nodded, eyes full of concern, "Either you turn her, or eventually..."
"Please don't say it Cake..." The very thought of Fionna dying pained Marshall in a way that Cake couldn't understand. Still he tried to reassure the concerned feline, "Like I said before, unless she asks me to turn her, I won't do it... much less bring up the subject, okay? It will be her decision, not mine."
Cake was moderately satisfied with his response; although she didn't want to see her sister become a vampire, she knew that Fionna's options were very limited if she were to continue her relationship with the vampire.
"Take care of my baby sister Marshall, I'll be seeing you at the wedding."
Awhile after Cake left, Fionna tip-toed back down stairs and peeked in at Marshall who was still sitting at the kitchen table; his eyes were closed and his arms were crossed behind his head, a pile of gray strawberries rested before him. He looked very content after having his fill of red, and Fionna couldn't help but smile at how peaceful he looked in the sunlight.
"MARSHALL! THE SUN!"
Marshall's eyes snapped open and he dove across the kitchen table into the shadows of the living room. Fionna immediately went to his side to check him for burns, and once the panicked vampire finally sat his ass down in a chair she was surprised to find not a single mark on him.
"No burns... you were in the light even before I came into the room!" Fionna exclaimed, "Marshall, how is that possible?"
"I-I don't know... I didn't feel pain or anything." He said softly, looking back over to the patch of sunlight where he'd been sitting. The pair was silent for a moment; and after exchanging a quick glance at Fionna, Marshall cautiously approached the sunlight. Bracing himself for sickening sound and smell of sizzling flesh, Marshall stuck is arm into direct sunlight... and nothing happened.
"What the hell?" Marshall said in disbelief, studying his arm after retreating back to the shadows. He looked back to see Fionna awestruck by this new discovery.
"How did this happen Marsh?"
Marshall pondered her question a moment, and then it dawned on him.
Sorry for the delay again guys, I'll have another chapter up soon. :)