"I bet I can go higher than you!" the boy in green shouts, but Kakashi doubts it. His dad gives him another push, his hands warm and strong on Kakashi's narrow back, and the trees fall away, replaced by blue blue blue.
Hearing Gai whistle, seeing his smile, a sliver of flashing teeth, Kakashi grins under his mask, a secret, hidden grin. And he is gone.
Ducking under a low-hanging shop-sign, hopping over a bench, dodging a food stall at the last second. Birds scatter when they reach the end of the village, the beginning of the forest, and burst into the foliage without slowing down.
The horizon jiggles up and down and Kakashi snorts and holds on tighter, his ankles pressing into Gai's thighs. They're too old to do this, but that is what makes it so fun, he thinks – not that he would ever admit the fun part out loud. Getting a piggyback ride as a silly challenge.
"We'll see how far you can carry me later, Rival!" Gai shouts, far too loudly, happy.
Unbeknownst to Gai, Kakashi smirks. This point will go to Gai, he's already decided that, but that only makes him enjoy the ride so much more.
The silver strands in Gai's bowl cut catch the light in new, shimmering ways as he cocks his head like he cocks his hip and grins, grins, grins, pointing at Kakashi.
"Rival!"
And Kakashi rolls his eye and sighs and flips a page in his not quite as dirty as he had hoped-book, because that's the way this goes, always goes, and drawls, "What?" although he knows the answer like he knows Gai.
"I challenge you!" Gai bellows, making heads turn in the street, earning giggles..
And Kakashi smiles under his mask where no one can see because he loves that answer like he loves Gai.