Tumblr word prompt by awesomeasusual. In which the mystery of Tsu's tats is explained.

scintilla: a tiny trace or spark of a specified quality or feeling.

Black Star didn't hit his much-delayed growth spurt until he was almost sixteen and she was four months from seventeen. In those four months before her birthday, he somehow managed to sprout five gangly, awkward inches in between eating the entire circus out of house and home.

So it was that Tsubaki was currently stuck staring grimly up at his foolish hair while he cheerfully sprayed bread crumbs all over her wagon. He caught her irritated glance and beamed, almost fumbling his food. "Finally caught up to you, didn't I?" he said with horrible smugness. "Told you I would."

She staightened her back and then, when that still didn't restore the world's proper order, she resorted to forcefully smashing down his hair until they were nice and equal.

"Cheating," he reprimanded.

"It's odd," she murmured, shaking her head and returning to her mending, settling Blair's torn skirt carefully in her lap as the wagon bounded energetically along. "I could swear just yesterday you were still… well, not tall." Was her brother taller now, stretching up as sky high and regal as their father had been? She pricked her finger with her needle and winced silently.

He shrugged and crammed the rest of his stolen bread into his mouth all at once, swallowing audibly. "Had to happen some time, didn't it? A god should be tall. My father was tall, if I remember right."

Tsubaki looked up at that, startled. Black Star never spoke about his family, or at least, he hadn't in years, not since he'd talked her into etching their sigil into his arm. "Oh, really?" she finally settled on, trying for a light tone, but her eyes kept straying to the shirt sleeve covering his lone tattoo.

He caught her eyes, again, and raised a brow. "You still feel bad about the damn tattoo? I wanted it. You know that."

"Yes." She sighed as she stabbed her finger again, when the train hit a particularly noticeable bump, and stuck it in her mouth as she laid Blair's skirt aside. "Come here, please." He complied silently and sank down on the bed beside her, watching with— miraculously— only half an infuriating smirk as she unbuttoned his overshirt and unhooked one suspender, pulling his sleeve down to his elbow.

The star tattoo was just as clean and neat as it had been freshly healed; she'd done good work, even through the blur of tears. "You never show it," she said, a little awkwardly, when he raised an eyebrow. "I was just wondering how it was holding up. Sometimes they blur after a few years."

"You used special ink, didn't you?" he asked unexpectedly, eyes narrowing.

She squeaked. "Um—"

"It smelled a little different than the kind you use when you do your own tattoos. I remember."

Damn the boy and his annoying observational skills. Still, though… Tsubaki tapped a finger gingerly over a still-healing scab on his arm, just below the tattoo, a souvenir from their last fight. As she touched it, her koi undulated gently up onto her palm, fins rippling gracefully, and she smiled. "It was different. For my tattoos I use an alcohol solvent and special metals for the colors. I used to trade for them with an oni girl I met in the mountains back ho— in Japan."

"You traded with a demon?" he said flatly, scowling and fiddling with his drooping suspender.

She grinned a little. "Yes." She could still see the oni girl, lost, shivering and even bluer than usual in the powdery mountain snow. All it had taken was a fire and a meal of trapped rabbit to spark up a friendship— well, as much of a friendship as a summer monster and a human girl could really have. But fresh meat for spirit metals was a reasonable exchange, and the oni girl had only tried to eat Tsubaki twice, which was really very sweet, considering how much she'd liked human flesh. "She wasn't that bad. I hope she's still guarding the mountains. She liked to make the flowers bloom early and they looked lovely in the snow."

Black Star snorted and rolled his eyes extravagantly. "A demon. And you tellme all the time that I'm insane."

"The first time she gave them to me they were a gift!" Tsubaki said, laughing a little. "I certainly wasn't expecting my first tattoo to start moving."

"I bet! So then what the hell did you put into me?" he asked as she traced his star again. Endearingly, the tips of his ears were vaguely red.

"The same solvent, but for the black pigment I used soot."

"That's it?" He seemed almost disappointed.

"Well. Not exactly," she admitted at last, finally withdrawing her hand from his tattoo. Her tiger, which had slunk down to her elbow as if to examine whatever it was taking up so much of her attention, gave a pink, gaping yawn and then curled up into a firey ball, tail flicking idly. "I burned a branch from home for the ashes. From the koyamaki that grew in the local temple."

He only blinked, and she could see that he hadn't made the connection. Probably it was to be expected. He spoke the language well enough, but he hadn't lived in Japan as long as she had. "Is that special wood?"

"It's a pine. I loved the pines back home," was all she told him. She didn't tell him that it was one of her land's five sacred trees, grown on sacred ground. The tattoo he'd wanted had such a bloody history, and his skin had been so golden and pure— she'd wanted somehow to give him good luck with blessed ink. The dry, aged pine had smelled so sweet when she burned it that she'd known it had been the right choice.

"Your mermaid's acting funny again," he said after a bit, flopping unceremoniously back onto her bed and staring at her ceiling, still only half painted with incomplete golden swallows.

Tsubaki scowled at the mermaid, who was waving her tail coyly at Black Star from Tsubaki's calf, and tucked her skirt down around her feet. The mermaid flailed silent protest as she disappeared from view. "Hussy!"

Black Star cackled. "When are you going to finish painting in here?"

"I don't know."

"When are you gonna do another tattoo?"

"I don't know. When I get a free moment, for once. Why?" she asked, amused.

He propped himself up on his elbows and looked at her from under deep blue lashes. "I like watchin' you make things."

Suddenly he wasn't so lanky and boyish. Suddenly, out of nowhere, he was tall and strong, and her breath caught at the look in his eyes. "I'll make something soon, then," she said, wondering at the quiet spark that had appeared from nowhere in her chest.

"Neat." With that, he promptly fell asleep, legs still hanging off her bed and mouth hanging gently open. She rolled her eyes and leaned over to take up her mending again, trying to ignore the window-rattling snores coming from her left. Astonishingly, he even managed to overpower the train.

Her tiger, her first, stretched lazily and sat up to peer with one bright eye from her forearm. She stroked him gently with a finger and he rolled happily onto his back. "For being from an oni, you're not so bad," she whispered.

If she had a demon's gift laced under her skin, it seemed only right that a being of light like Black Star should have sacred ash beneath his. She paused in her stitching to press a hand to her heart, over the secret spark, and if she didn't know any better, she'd almost say it was beating in time with his prodigious snores.