Title: Understanding the Cosmos

Pairing: Jack/Yusei

Rating: PG-13

Summary: Sometimes to understand yourself, you need to go back to where you started. For Jack, that place is with Yusei.

Crow and Kiryu had long since retired to bed – it had been a long day, and they were all feeling the effects. Jack was pretty sure he was going to crash hard too, as soon as the adrenaline pumping through his body wore off, but he wasn't quite there yet. Yusei was still up as well, sitting at his side, though Jack imagined he must be just as exhausted as the other two. It'd been a difficult, drawn out hunt, followed by an even more drawn out, difficult duel, but Team Satisfaction's undefeated legacy still stood; would surely continue to stand.

Today now marked the day that Team Satisfaction had conquered over half of Satellite, more black marker than white on their map, and suddenly this mission they'd taken on – a mission that had once felt like little more than a pipe dream – seemed more within their reach than they'd ever imagined. Halfway there – they'd reached the top of the mountain, and all that was left was the climb down.

The thought left Jack's spirit burning.

Yusei seemed much calmer about the whole thing, but that was nothing unusual. Since childhood, Yusei had always been this way, a steady pillar of calm with a good head on his shoulders who liked to sit back and assess the situation before he acted. He didn't seem as excited by the events of the day, but still, he sat up with Jack by the fire they'd built hours ago to ward off the chill of the bitter Satellite winter nights.

"You should go to sleep," Jack finally told him, and his I-know-best tone was shamelessly bossy, demanding, to mask the fact that he was showing concern for another human being. "It's been a tiring day."

"Same goes for you," Yusei replied. Then after a moment, "I'm not really tired yet."

"You're always like that," Jack argued. "I say you should go to sleep. You know you'll pass out the moment you lay your head down."

Yusei gave a short, soft chuckle. "Maybe that's so."

Jack glanced at him out of the corner of his eye. Yusei's profile was lit from the orange glow of the fire, light from the flickering tongues of flame glinting off his eyes. He'd grown up, Jack suddenly noticed. He saw him every day and, as such, it had been a long time since he'd bothered to really look at Yusei. But now, doing so, he realized with a start that his features were much sharper, his eyes more shrewd, and the roundness of childhood gone from his face. He was beginning to look like an adult, and Jack wondered how he'd failed to notice until now.

He realized too late that he was now staring quite blatantly, but when Yusei's gaze caught his, he didn't bother turn away, shames and unabashedly continuing to look at him. Yusei cocked his head in lieu of a question, but they'd known one another almost their whole lives now, and that was long enough for them to be able to read one another's body language as easily as words on a page.

"You've changed," Jack said, answering the unspoken query, and Yusei smiled a rare half-smile.

"Have I? In what way?"

"You're getting older."

Yusei's smile grew, and Jack's heart gave an odd thump.

"I hope you didn't expect me to stay a child forever," he said, deadpan as ever, to the point that someone more unfamiliar with him may not have taken his comment as a joke.

Jack flushed. "Don't be idiotic. Of course I didn't. I just…" he paused, and on a whim reached out to brush his thumb along a newly-prominent cheekbone, and then down over a stronger, more defined jaw. "…just didn't notice it happening."

"Ah." Yusei nodded, and then when the fingers pressed to his face stayed where they were, he looked up again, their eyes locking. "Jack?"

Jack felt his heart quicken, and the feeling that came over him was unfamiliar, tingled in the pit of his stomach like soda bubbles. He moved his hand to fully cup Yusei's cheek, and his chest squeezed tight when Yusei's expression melted into something softer, less guarded. "Jack…"

"When…" Jack murmured, leaning in, taking Yusei's face in both hands, "When did you grow up so much?"

"Does it bother you?" Yusei asked, voice soft and eyes not leaving his.

Jack shook his head. "No," he answered honestly, and his heart felt so full of these strange, foreign emotions that it almost ached.

It was Yusei who leaned in first and pressed his lips to Jack's, the kiss chaste and gentle, almost cautious, and it reminded Jack of the way Yusei dueled an unknown opponent, taking the first turn to assess them, test the waters. Jack stared at him in bewilderment when he drew back, eyes a little hazy and face flushed.

"Yusei…" he fought to resist the urge to bring his fingers to his lips. "Why…?"

Yusei shrugged, his gaze back on Jack, unwavering and unapologetic. "You looked like you wanted to." Then, as an afterthought, added, "I did too."

He took a second to consider these words, and it dawned on Jack that that's what the strange feeling from earlier had been. Yusei wasn't wrong – he had wanted it. Wanted more.

"Show me…" Jack whispered, fingers threading through dark, gold-streaked hair. "Show me just how much you've grown up."

Yusei didn't refuse as Jack drew him closer, taking what he wanted just as Jack Atlas always did, and their mouths met again, in a clumsy clash of lips, then tongue and clicking teeth.

They both grew up a little more that night.