As promised, something in universe.
Disclaimer: I own nothing.
"Oh my glob, I'm so bored," Finn complained to the air. Jake was baby-proofing Rainicorn's house, BMO was at soccer practice, Marceline was in the Nightosphere, Treetrunks was with the pig, Flame Princess was at some Fire Kingdom event, and Bubblegum was just plain busy.
When the phone rang, it was like his feet had wings.
He tripped and fell flat on the floor, knocking over the phone. Fumbling for it, he held it to his ear.
"Ugh...hello?"
"Hello, Finn!"
"Peebles! Man am I glad to hear your voice! I've been soooo bored all day and—"
"That's great, Finn. I need you to come to the lab right away!"
"Um...okay?"
"Great! I'll see you soon," she hung up, and Finn started for the Candy Kingdom.
"Math this!" he sprinted all the way there. "HIYAH! What's up, Bubblegum?" he somersaulted into her lab and politely shut the door behind him, turning to see... "WHAT IN GLOB'S GOOD NAME IS THIS?" there was a totally random hot tub right in the middle of the lab! Marceline and Bubblegum were lounging in it, eating strawberries.
"So...does Finn know yet?" Marceline was asking.
"Do I know what?" but they ignored him.
"No," Bubblegum blushed.
"Ugh, Bonnie! You gotta tell the kid! I mean, you do that to him while he's unconscious—"
"Do what?"
"—which was really clever, by the way...wish I'd thought of it. But then again, you always were the feminine one," Bubblegum blushed again. Finn walked over and waved his hands in front of their faces, but they didn't even blink.
"I don't know if that's a compliment or no..."
"Well you always let me be on top," Finn's jaw dropped when Marceline paused to drink the red from the strawberries, "when we were arguing," he sighed with relief, "and—"
"Marceline, we agreed to never discuss that again!" Bubblegum chided.
"Oh yeah," she pondered. "Even though there's nobody here?"
"Which is a little odd...I called Finn like ten minutes ago."
"I'M RIGHT HERE!" Finn screamed.
"Think he's listening in?" Marceline asked.
"Go check!" Bubblegum urged. The vampire floated out of the hot tub, and Finn's jaw fell slack again; she was wearing a black and red skull patterned bikini that showed exactly how pale her skin really was. After adjusting her top, she floated to the door, and Finn admittedly had his eyes on her behind the entire time.
"Nope, nobody," she said, turning around and frowning.
"Huh. You sure?" Bubblegum climbed out to walk over, and Finn's eyes moved to the pink princess, whose bikini was a very brilliant shade of fuchsia.
"Positive."
"Hm...maybe he got caught up fighting a monster," Bubblegum said thoughtfully.
"Or maybe he just ditched us," Marceline snorted. Finn's jaw dropped for the third time.
"WHAT?"
"Finn would never!" Bubblegum gasped.
"News flash, Bonnie; not everyone's a perfectly loyal little pal," she sounded like she spoke from experience. "Some of them are just waiting for the right moment to turn around and betray you," Finn walked over and laid a comforting hand on Marceline's shoulder, but she didn't seem to notice.
Oh yeah...I'm not here. Or am I...? deciding to test his theory, Finn grabbed one of the strings on each girl's bikini top and pulled.
"EEP!" Bubblegum squealed.
"What the flip?" Marceline shouted. "Argh! I told you we shouldn't have gone to Choose Goose!" Finn's spirits fell. He wasn't here.
"Here, tie me back up," Bubblegum held her top up with one hand and her hair with the other. Marceline let her own top hang limp, grumbling under her breath as she tied Bubblegum's bikini strings. Finn blushed, but reasoned with himself that he had already seen her once, so what was one more time?
"Now you tie me," Marceline turned around, having to use both hands to hold up her hair. Bubblegum reached around to find the strings, and all three of them shivered, Marceline especially.
"I'm cold," Bubblegum complained.
"So get back in the tub," Marceline rolled her eyes.
"Aren't you coming?"
"Nah..." she grabbed her guitar and floated on her back. "Think I'd rather play something."
"Ooh, about what?"
"Hm...just a little song called Can I Have A Kiss from before the Mushroom War."
"You know of music before the war!"
"Bonnibel. I existed before the war. I'm like an encyclopedia," Marceline rolled her eyes and started to play.
Is she...singing about me? No, no, no way.
"And this one goes out to Ash. It's called You Love Me, by the same chick, Kelly Clarkson."
"Haha, she is too good for him!" Finn said aloud.
"Einstein, same gal, also for Ash, and another two for Finn and Flame Princess; Already Gone by Kelly Clarkson again and Gone Forever by Three Days Grace."
"Aren't you tired?"
"I'm just warming up!" Marceline grinned and started to play again.
Is she trying to tell me something here?
"Ooh here's a totally random one; Hug Me by Meg & Dia," some of the lyrics made Finn a little embarrassed, but there was one line that made him think...
Does Marcie...like-like me?
"Ugh, this top is too tight!" the vampire complained.
"So?"
"'So?' Bonnibel, uncomfortable vampires are likely to bite. I'm taking it off."
"What!"
"You heard me," Marceline reached back to untie her top. "And by the way, about what we were first talking about...seriously. When are you gonna tell Finn you're pregnant?"
Finn nearly passed out.
"And that, Finn," Bubblegum said, "is how you pull off a perfect prank."
"What? I—you—the—it—what?"
"We pranked you, weenie. Now tie on my top," Finn positioned himself behind Marceline and reached in front of her, feeling her shiver as he grabbed the strings. After he tied on the top, he just couldn't resist pressing a kiss to the back of her neck, which was just his height. Marceline squeaked. "What was that?"
"I don't know what you're talking about," Finn pulled off his shirt, shoes, and socks and jumped into the hot tub, sliding an arm around Bubblegum and kissing her cheek.
"What about Flame Princess?" she asked, blushing.
"We broke up," was his casual reply as Marceline nestled herself into his other side. He slid his free arm around her shoulders and pulled both girls closer. They leaned their heads on his shoulders.
Too bad I can't have two girlfriends, he thought mournfully.
"That prank wasn't funny, by the way," he said.
"Yes it was," Bubblegum argued.
"Wasn't."
"Was," both girls said in unison.
"Wasn't."
"Was."
"Wasn't."
"Was."
"We should've done the other one, though," Marceline smirked and Bubblegum blushed.
"What other one?" Finn asked.
"I'll tell you when you're older."
"Marcie!"
"Finn!"
They all laughed. Marceline grabbed two strawberries from the abandoned bowl and drained the red from them, popping the now gray fruits into the mouths of Finn and Bubblegum.
"You know what?" Marceline asked.
"What?" Bubblegum replied.
"We need to hang out more."
"She's right," Bubblegum told Finn. "I like you both...a lot. We need to do this more often."
"Jake's gonna be out with Lady tomorrow, and BMO's got a soccer tournament. We could watch movies at my place?"
"It's on," Marceline grinned and popped another strawberry into his mouth. Bubblegum pouted. "Needy, much?" they laughed. "You ever wonder...? Nah, it's stupid," Marceline blushed.
"No, nothing you say could ever be stupid," Finn told her sweetly. Bubblegum nodded.
"If...we could be something more? Dumb, right?"
"Nah, I was actually thinking the same thing. Princess?"
"We are something more; we are all very close friends. And that's how it should be," but the glance Finn and Marceline exchanged said that there should be something more.
Something stronger.
Marceline and Finn like-liked each other, he knew, but he also like-liked Bubblegum! He needed two girlfriends. Why was Bubblegum so opposed to progress?
"So...movies tomorrow?" Finn asked lamely.
"I totally call sitting in Finn's lap!" Marceline said quickly. The human blushed.
"Then I call cuddling up to him," Bubblegum smiled with her eyes closed.
And that was all Finn needed to hear.
The roadblock had moved aside.
He could move in.
But not today.
Not today.
Tomorrow...