It's not until the second week that Gokudera is sure.

The first few days could be a fluke. After all, Yamamoto is friends with the Tenth, and even if Gokudera is his right-hand man now it's reasonable that Tsuna might have lingering acquaintances from before they met. Maybe it's just that Yamamoto lives near the other boy, that he happens to leave for school at the same time Gokudera does so they always run into each other. Maybe it's just coincidence, or spectacularly bad luck on Gokudera's part that he seems to summon Yamamoto as surely as a storm brings rain. He tests that idea first, tries to break the habitual connection by leaving a few minutes later than usual each day. Finally he's coming into class late and getting a glare for his troubles, and even then Yamamoto is always there, hovering at his shoulder and laughing at things that aren't funny, his presence inevitable and apparently unavoidable.

So Gokudera tries early. The first day he's jumpy the whole way to school, keeps peering over his shoulder for the jogging footsteps he can recognize a block away, now. But they don't come, are as absent as the laugh that felt everpresent in his life, and when he gets to school an hour early he sits in the library hunched over a book he's not reading and tells himself he's glad for the silence. It's not until the first class that he catches the peal of laughter around a corner just out of sight, and he's jogging to glance down the hall before he can think why he's in such a rush. It's Yamamoto, of course it is, as warm and glowing with unfettered joy as he always is, and he doesn't say anything about Gokudera's absence that morning, doesn't acknowledge the other boy in any way outside of his usual constant presence. Gokudera is out of sorts that whole day, short with the Tenth and entirely ignoring Yamamoto, and by the time he gets home he doesn't bother doing anything but crawling into bed and glaring at the wall until he manages to chase down sleep.

He's tetchy the next morning too, barely bothering with breakfast and not at all with doing up the buttons on his uniform sweater. It all seems useless, a waste of time and effort so immense he almost goes back to bed and doesn't bother with school at all. But he can't sleep anymore, and school has some bittersweet pull on him he doesn't quite think about, and in the end he tells himself the Tenth needs him and drags himself out the front door. He doesn't look around like he usually does, doesn't brace himself for his usual company, and he's staring at the ground in front of the opened gate without seeing anything when a voice catches all his attention.

"Yo, Gokudera!"

Gokudera's head snaps up even though he doesn't need to see the face to place that chipper tone. Yamamoto is smiling at him, all his usual easy delight written in every line of his features, and Gokudera can feel his shoulders go slack, can feel tension draining out of him before he can pull its protection back around him in the form of a glower as he lets the gate slam shut behind him.

"What are you doing here?" He steps away, setting a pace slightly too fast for comfort. There's the rhythm of a jog, Yamamoto falling into a run for a moment to catch up to him, and then an elbow brushing his arm, a shoulder bumping again his shirt in the clear light of the morning.

"Waiting for you," Yamamoto says, like it's obvious. "I missed you yesterday."

Gokudera skips a step, stubs his toes on nothing and nearly falls before he can save his balance. Yamamoto pauses for him, Yamamoto's fingers catch at his elbow, and for a moment Gokudera can feel that contact sparking all up his arm before he jerks his hand away.

"What?" He crosses his arms over his chest, glares sideways at the other boy. Yamamoto is watching the path in front of them, smiling like he doesn't know the meaning of worry, like his smile is lighting up the day more than the rising sun. "You missed me?"

"Yeah!" Yamamoto looks at him, then, turning the full force of his unthinking smile on Gokudera so the other has to look away as his cheeks start to go warm. "You left for school early, I didn't realize until it was too late."

Gokudera takes a breath, can feel it catch weirdly in his throat before he coughs to clear it. "You didn't have to meet me," he grumbles at the ground. "It's not on your way this early in the morning."

"I don't mind! It's not on my way anyway," Yamamoto offers blithely. "I live on the other side of the school from you."

Gokudera stops. Yamamoto starts to walk past him, takes a pair of steps before he realizes the other has stopped and turns to face him. His eyes are wide and innocent; they catch the light into gold without a trace of self-conscious shadow even though Gokudera's skin is flashing hot and cold with suspicion and doubt in equal parts.

"It's not on your way?" he says again, repeating back the words just to make sure he's not coming to the wrong conclusion through some idiocy of Yamamoto's.

"Oh no." Yamamoto tugs the strap of his bag higher, tips his head and grins. "I come out to meet you."

Gokudera's hand comes up, his fingers close around the crisp white of Yamamoto's shirtfront. "What?" When he drags Yamamoto leans into the pull, his smile breaking into a laugh as he holds his hands up like he's surrendering. "Why?" Tipped forward Yamamoto is nearly at eye level, his natural advantage of height all but lost to the angle and the force of Gokudera's confusion. "Why do you meet me?" He punctuates with a shake, hard enough that Yamamoto flinches. "Why do you know my schedule?" Another shake, rougher and more desperate. Gokudera can feel his voice breaking into hysteria, can't stop the high wail of sound in his throat. "Why do you follow me, why are you always here?"

Yamamoto is still smiling, his expression so soft Gokudera feels a surge of instinctive guilt at the violence of his words. His face is bright in the sunlight, it's catching his hair into inky shadow and his eyes into sparkling light.

"Because I like you." The words are simple, the meaning feigning unimportance with how easily Yamamoto says them, like they're not the confession they are. But Gokudera feels them like a tiny explosion in his chest, like everything in him is seizing up in a panic of adrenaline, and Yamamoto's eyes are going darker, until when he blinks there's something there besides his usual foolish delight. "A lot."

Gokudera can't get his hand to let go. All the frustration under his skin has gone slack, has left him adrift and lost until he can't tell what's reality and what invention, can't pull apart reason from hope or his own interpretation from Yamamoto's intention. For a moment they're both still, Yamamoto with his hands still half-raised and Gokudera's fingers going numb with the force of his grip. Yamamoto is watching Gokudera's face, his lips soft around that smile, and Gokudera can't close his mouth, can't form words on his tongue or thoughts in his head.

Then Yamamoto blinks. Gokudera is staring at him, desperate for something to catch onto, some spark of certainty amid the doubt overlaying all his interpretations, and so he sees the tiny flicker of motion, sees the way Yamamoto's eyes drop to his mouth for a moment. His skin flushes hot with self-conscious awareness, and he's not sure if he's pulling on Yamamoto's shirt or if it's the other boy leaning in to shorten the distance between them as his lips part around the shape of expectation. Gokudera's heart is racing, his breathing coming painfully short in his chest, and he's not ready for this and he's not sure what to do, but he can't get himself to shove Yamamoto away.

Then the other boy blinks again, his eyes come back into focus, and he's leaning away, his shirt sliding free from Gokudera's hold like it was a gentle touch all along.

"That's all!" He's smiling again, still watching Gokudera's face, but his eyes seem darker, his mouth suddenly magnetic for how hard it is for Gokudera to look at anything else. Gokudera has to turn away, has to start walking fast to keep his eyes on the path and off Yamamoto's features; there's the sound of footsteps, fast for a half-jog, and then that brush of contact again, an elbow a little too close to Gokudera's so it brushes his sleeve.

Gokudera growls. "Idiot." He's still staring forward like that'll keep him safe from Yamamoto's smile, but his skin is tingling through the layers of fabric. When he lets his weight swing sideways his arm bumps against Yamamoto's, lines the pressure up into something very close to deliberate for a long second.

By the time they get to school, Gokudera is no closer to finding a solution for the situation. The only advantage - and he doesn't think about this, carefully avoids the thought the entire time Yamamoto is next to him in the library before class starts, the entire time he is ignoring the way his skin flares hot with every accidental touch - is that the other boy's presence doesn't seem quite so unbearable, now.

He thinks there might be worse things to have in his life, after all.