I was writing a few fics of Finn and Marceline having a baby on Tumblr, and I was inspired to do something related to Flame Princess with them after watched 'Vault of Bones'.
Disclaimer: I do not own Adventure Time, or make profits thereof.
Flame Princess walked nervously into the room, her flames kept at a low pulse and her footsteps leaving sparks.
Marceline hovered just to her side and Finn to her other side, and it felt strange to see him smiling up at her from somewhere around her hip. For a moment, the thought was a little sad; as she had grown immense over the years, they had grown a little apart, Finn not her boyfriend and romance like she had hoped.
The Vampire Queen moved next to her, sliding from her to Finn, and Flame Princess smiled faintly. Finn was her friend, and Marceline was too. She felt better about it. Finn reached up and indicated her towards the crib in the room. "G'wan," he said, making a urgent motion towards it.
Flame Princess paused, just for a moment, but it felt like it stretched for hours. Just a little hesitation, enough to make her feel ill at ease and tremendously unsure.
"Go on," Marceline said, dryly.
Flame Princess bit her lip. "Are you guys, y'know... sure about this?"
Finn and Marceline nodded, virtually as one. Flame Princess wondered briefly if she'd ever meet someone as in tune with each other as Finn and Marceline were, and concluded that it wasn't a matter of just meeting someone, but of knowing someone for years, being their friend, growing with them, learning and sharing experiences, and becoming closer until friendship and romance were inseparable.
She relaxed, flames cooling to a less erratic form. Shelving the thought aside, she instinctively raised a hand to Finn, to touch his shoulder. She jerked back at the last moment, almost forgetting how fragile humans were (at least compared to fire elementals). But Finn reached up, clad in special magical garment she hadn't realized the importance of until now, and though she was still so large that she had to duck nearly double to fit under most doors, her hand was still low enough for Finn to grab and squeeze her hand warmly (and no one knew warmth like a fire elemental did).
"It's okay," Finn said, smiling. "She's tough like Marcy, Peebee made sure. Your flames can't hurt her one little bit."
Flame Princess worked her jaw, light shedding from her in orange-red radiance, and a chubby cheek puffed out. "You sure? You guys, you're making a pretty big risk here."
"Nah," Marceline said diffidently. "You're our bud. Heck, you're family." She grinned, teeth sharp like knives and welcoming for all of that. "The cornpups have been calling you Auntie for years. Shoulda already gotten used to being part of the thing."
Flame Princess snorted. "I dunno," She said.
"You have all the confidence of a dead owl-bear," Marceline said, giving her a little push.
"But owl-bears are lame!" Flame Princess protested. "They're part bear and part owl! What do they need the owl for, bears are already awesome! What's next, a bunny-snake?! Or a lion-turtle!?"
"Actually, lion-turtles exist," Finn said. "They're pretty awesome! Come out of nowhere and spook people that mistake them for islands, but awesome."
"Not the point-" Flame Princess started.
"Go on," Marceline said, giving her a none-too-gentle shove, pushing her down the room (the floor treated against burning, fortunately, but Finn and Marceline had prepared their house to be proof against the various difficulties and compositions of their friends, including Flame Princess).
"But-"
"Go!" Marceline said, more forcefully.
Flame Princess made a face, and then her flames brightened a little bit. "Okay, okay…"
Her immensely tall and broad form, in the image of the fire giants that were her most illustrious ancestors (going all the way back to Loki Liesmith, the genealogies said), illuminated the room as she walked down it, long legs settling into a measured stride, and aware of Finn and Marceline lazily watching her. For a moment, she assumed it was because they didn't trust her, and the thought hurt even as it came on the awareness that this was a reasonable doubt… and then, the naked curiosity in Finn's face, it occurred to her that perhaps they simply wanted to see what she would do, and how she would react.
Her step quickened, even though she felt so nervous she wanted to run away and hide in someone's fireplace until the sun exploded. She didn't understand her feelings, or why she felt strangely excited and scared at the same time.
Soon, she loomed over the crib, her light dispelling the darkness inside. "Um," she said, and felt incredibly stupid for not being able to come up with anything else, but she faltered at just that. Better words refused to appear, though their possibility lingered in her head, tauntingly. "Um."
A tiny form shifted around in there. A pair of eyes, a mild shade of greenish-blue and shockingly human, fixed on her face.
A gurgle from the crib, and a heavy blanket shifted aside as a pair of chubby hands raised up to her, inquiringly. "Oh!" Flame Princess blurted out at the tiny human there (perhaps not human, exactly, but when a human and a vampirized human-demon hybrid bred, it was difficult to be sure what you would get). "Um…" She looked back, helplessly. "Guys! The stuff am I supposed to do?!"
Marceline scoffed. "Wimp," she said, but not unkindly, a friendly teasing, and Flame Princess had gradually gotten used to that from her over the years. She floated over, Finn following behind her and his footsteps a mirror of the regular friendship party going on over head; he still threw one every so often without prediction or regularity, because having their family dropping around like that was just how he and Marceline rolled.
The Vampire Queen and her prince-consort came around, and her gray-blue hands dove into the crib. The baby inside made little infant-noises as Marceline picked her up, eagerly clamping onto her; a girl, skin much darker than Finn's though not as dark as Marceline claimed her own mother had been, and hair a dull shade of brown. Chubby, like a little bag of Finn-like flesh, she looked like a lump on Marceline's front.
"Here," Marceline said, picking up her baby and passing her over to Flame Princess. The infant bounced and squirmed in Marceline's hands as Flame Princess instinctively picked her up.
"Ah!" Flame Princess blurted out, flames flowing harmlessly around the chubby little baby. "What am I supposed to… oh geez!" She brought the baby close, supported her against her chest and placing an arm around the baby's backside, propping her up against her. "Geez, don't… give me some warning!"
Finn giggled, eyes bright. "You're pretty good with her, Eff-Pee!"
Flame Princess blinked. The baby curled against her, snuggling into her bust, and Flame Princess' eyes went wide at this. The baby curled in, blinking up in dim interest at Flame Princess, looking so small and tiny; she fit neatly into her hand, so big was the princess of the Fire Kingdom. She felt… warm and soft, like Finn but of a different flavor.
Flame Princess' expression softened, and she hugged the baby, her thick arms soft against the fireproof infant. Her inner flame warmed up, sending pleasant pulses through her elemental matrix, and Flame Princess giggled. "You know… this feels pretty nice."
She couldn't remember the last time she had actually held something, and never something as cute and sweet as this. She sniffled, smiled, and off-handedly blinked away a bright liquid-flame tear. "…Thanks, you guys."
"She likes her auntie," Finn said, smiling at her.