There wasn't much time to prepare. "Better bundle up!" was all Marceline said, cheerfully tossing a jacket into her arms. Fumbling with it, Bonnibel barely had time enough to slip her arms through the sleeves before Marceline scooped her up into a bridal carry, flying across Ooo faster than she could keep track of the landmarks. All she knew was that they were flying at an alarming altitude and very, very fast. Shrinking closer to her consort— "consort" because "Girlfriend" sounded too juvenile and "partner" too serious— she stammered something about her flu and the night air being too cold, but Marcy smelled that bullshit two miles away and laughed at her, relaxing her grip just enough for Bonni to panic a little.

"You're not really scared of heights, are you?" They climbed higher into the clouds, bursting through the dark vapors to emerge at the clear, smooth area above them. "You ride Lady and the Morrow all the time and never get all shrinking violet on them."

Bonni sneezed, not enjoying the dampness that now clung to her clothes. "Not this high," she complained. "And now I'm cold and wet. So, thanks. For that."

Taking that as a cue to slow done, Marceline kissed Bonni's cheek in apology. Twirling midair, she flew with Bonni resting on her stomach, straddling her waist. "Told you to bundle up," she said, letting the princess sit up enough to finish buttoning her jacket. "We're going on a date tonight, missy."

Her nose red as a fresh cherry, Bonni sneezed again. "You scoundrel," she said, affectionately. "Wasn't I supposed to be bed ridden for another week? I can recall something along those lines involving your teeth, and a very frightened doctor making sure that was my diagnosis."

Either windswept or embarrassed, Marcy's cheeks began to flush with color. Her hands laced together under her head, putting less strain on her neck and giving her the appearance of lying out somewhere— a mossy meadow or a cave floor, not several thousand yards above the ground. "Yeah, well, you need a break. One week of no work. P-Butts can take care of things with the notes you gave him, right?"

"Right."

She kept pressing. "And you got sick because you stressed yourself out too much, right?"

Bonni rolled her eyes.

"Okay, well, you get my point. One week. Or at least five days." Reaching up to grab her, she pulled the princess down so their torsos were resting against each other, tucking Bonni's head under her chin. Once she was secure, Marceline sped up their flight. "Consider it an early vacation."

It wasn't long before they set down on the edge of a sinkhole, far beyond the borders of her kingdom. Getting down on her hands and knees to peer over the edge, Bonni was faced with an infinite blackness, and no sign at all of what had caused this seemingly endless pit. This was their date, it seemed. An adventure in spelunking, for no doubt this opening in the ground led to some sort of cavern deep below. "Shouldn't we have bought flashlights?" Bonni asked, experimentally dropping a pebble into the pit and waiting to hear it sound back as it hit the ground. There was no response.

"We won't need em, eventually," Marceline promised, extending her hand to Bonni to help her up. Shrugging, Bonnibel wrapped her arms around Marceline's shoulders, stepping close and nodding quick. Holding her tightly, Marceline leaped over the edge and started descending, slow and easy to not frighten Bonni.

The light grew scarce, the inky night swelling around them. For a while Bonni could just look up to the shrinking circle above them to catch a glimpse of the night sky, but eventually they came to a curving U loop and that was lost as well. There was no difference between keeping her eyes closed or open any longer, so she just clung to Marceline, reassuring herself in the sensation. "This place used to be a mine," Marceline whispered, probably realizing that the darkness could become suffocating for someone not used to it. "Or a shelter that eventually expanded out, I'm not sure. But they didn't dig smart, and the ground fell down around them."

Not exactly the best thing she could have chosen to say. Maybe she was actually trying to freak Bonni out.

In a way, though, it was very peaceful. The hushed sound of her own breathing, her own heartbeat, and the stillness of Marceline's body coupled with her exhaustion to lull her to the edge of sleep. She hadn't been lying when she said she was still feeling the aftereffects of her flu, and was glad that she didn't have to walk anywhere. And the longer they were down there she realized that even here, there was life. Small, scratching bugs; the occasional bat flapping past, wingbeats loud as thunder in the subterranean emptiness.

Then they stopped.

Marceline set her down, keeping one hand on her shoulder so she wouldn't get lost. A dozen small rocks clattered underfoot, shifting and rolling with each step and making the path hazardous. She wondered why Marceline wasn't still carrying her, until she felt the vampire press one of the rocks into her hands. It was roughly the size of her palm, flat and disc-shaped. Pleasantly smooth and round, it rolled under her curious fingertips but did not seem to be special in any way.

"Blow," Marceline said in a low voice, very gently bringing Bonni's hands to her face.

So she did.

Light erupted along the stone's surface, pale sea-blue with jade splotches so dark they seemed like ink stains. Dropping the stone with a start, she took a few steps back on the shifting waves of the rocks pinching at her feet. Laughing, Marceline steadied her before she tripped, giving her another rock. "Do it again!" she commanded, grinning with all her teeth.

Bonnibel did it again, ready this time and giving it a long, even gust. The rock dazzled up at her again, salmon pink surrounded by wavering, buttery concentric rings. Setting it down on the ground next to the blue one, she grabbed another rock and eagerly blew a short puff on it. The results were a little disappointing. "This one looks exactly like glowing mucus," she announced, tossing it aside.

"They can't all be winners."

Bending down, Bonnibel gathered an armful of the strange little stones, sounding a low "Ahhhh" over them and grinning at the rainbow that tumbled out of her hands, sprinkling back onto the floor. "This is so cool!" She said. Noticing that Marceline was just watching her reaction, she wondered how many other people she had brought down here to play among the spectrum stones (as she had dubbed them in her mind).

Picking one up herself, Marceline whistled at it, the corners of her mouth turning down in sadness. "It never works for me," she said, turning it over in her hands, this way and that, over and over, as if she could deconstruct the mystery. "Only a living breath will do."

"What are they?" Bonnibel wondered, her words coloring a blood-red splotch that gradually lightened out into an orange sunset. Not waiting for an answer, she began to puzzle out their function for herself. "Maybe they react to carbon dioxide, and that's why they don't work for you. You don't actually need air, right?" Marceline nodded. "So you don't need to convert it inside your body, and it returns to the environment just as it was every time you speak, or do any other activity that requires air to travel through your larynx."

Tilting her head to and fro, Marceline measured the thought. "Could be. I've never really thought about it." Twisting her hands together, Marceline fidgeted even more with her stone, which refused to kindle under her dead breath. "Do you like it?"

"These?" Bonnibel asked, letting another handful of glowing rocks rain between her fingers. "I love it!" She tossed more into the air, confetti clacking as it struck its fellow on the cavern floor. Lost in her enthusiasm, she continued to test the rocks to see if any patterns emerged, if a warm, wet sigh produced a different hue than a thin stream of air. The shadows had long since receded, replaced by the aurora borealis she had constructed herself. "Can I take some home?"

"Would you like to?"

Bonnibel responded by bending over double and coughing. It was deep, and wet, and shook her whole frame. An unexpected reminder of the sickness that still held her under its grip, it didn't let go until she had spat out the gunk clogging up her chest. "Ewww," Marceline teased her even as she rubbed at her back. "You're right, that stone did look like mucus."

"Oh, shut up."

"Seriously though, you okay?"

Not willing to talk more than she had to, Bonnibel nodded.

"Wanna go home and maybe come back another night?"

After a pause, Bonni nodded again, leaning forward to rest her head on Marceline's shoulder. Stuffing some of the stones in her pockets, Marceline picked Bonni up without another word and returned the way they had come. The trip back was more leisurely than their initial flight, Marceline trying to go easy now that she realized she might have pushed Bonni too hard even as she had tried to get her to loosen up from work and have a little fun. They rose from that yawning black hole to fresh, inky midnight skies. The moonless night seemed bright in comparison to the caves. Again Marceline turned in midair so that Bonni was seated comfortably atop her belly, since she wasn't sure riding piggyback wouldn't tire her out. Besides, it was cozy. Seeing Marceline's face clearer than ever as she flew them home, her eyebrows furrowed in concern over her well-being, Bonni was uncomfortably aware of the affection blooming inside her like an ivy branch, threatening to spill out of her mouth and completely envelop her. "Thank you for taking me out, Marcy," she said, leaning down to hug her so that she didn't have to look into her worried eyes any longer.

Surprised, but not complaining, Marceline held here there by the back of her neck, planting a kiss on top of her head. "No problem."