Yamamoto is used to being insulted.
It didn't used to be a part of his life. He's been relatively popular during the course of his school career, well-liked and friendly enough to avoid any real jealousy or distaste from his classmates through the years of school. He was used to considering everyone a potential friend, ready to take casual affection for granted from all those around him without thinking much of it.
Then he met Gokudera Hayato, and his entire life reoriented itself. The friendly acquaintances he used to spend time with were forgotten, easy camaraderie a thing of the past. He learned to answer to 'baseball idiot' as quickly as to his given name, learned to breathe faster at a hiss of irritation more than at a laugh of satisfaction, recalibrated every part of his life to coordinate better with the hissing, spitting, furious perfection that comprises Gokudera. It's not that he likes the abuse; it's that he likes Gokudera, has never liked anything as much as he likes the other boy, and whatever that entails is something to be loved too.
He's learned the nuances of Gokudera, too, has put his attention to learning the forms of the other boy's irritation like he's learning the signs of a new play in baseball. He can pull apart true frustration from just the appearance of it, now, can hear the edge of affectionate unconcern in the tone of the other's voice, until insults in Gokudera's throat can make him smile wider than compliments in another's.
So he knows, when Gokudera huffs from the other side of the room, "What the fuck are you even watching?" that it's loneliness under the words, boredom and isolation that are pulling him to stand in the doorway with his arms folded like a wall in front of his chest.
"The nationals," Yamamoto says aloud, sitting up on the couch so there's space for the other to sit when Yamamoto leans over the back of the couch and reaches to gesture Gokudera in.
"I can't believe you're watching this," Gokudera huffs, but he unfolds his arms and comes in to the couch. He doesn't take the offer of Yamamoto's hand, but neither does he flinch away when the other drops his extended arm over the other boy's shoulders and leans in to rest his weight against Gokudera.
"It's fun," Yamamoto says, ducking his head to press his mouth against Gokudera's shoulder. He hits fabric instead of skin, breathes damp against the cloth rather than dragging a kiss across the heated texture of the other's body, but Gokudera tips in anyway, some of his tension giving way to the contact of Yamamoto's mouth anyway. "Watching the game is the next best thing to playing in it."
"God," Gokudera huffs, reaches out to dig his fingers into Yamamoto's hair without pushing hard enough to urge him away. "You really are a baseball idiot."
Yamamoto has to laugh at that, disagreement spilling warm and affectionate in his throat. "No I'm not."
Gokudera scoffs, glances sideways so Yamamoto can see the lopsided smile at his lips, the bright light in his eyes. "You can't even see how obsessed you are."
"That's not true," Yamamoto protests. He reaches out with his free arm to loop it around Gokudera's shoulders, turning his back to the game so he can catch the full force of the green of the other's gaze instead. "It's just not baseball. I'm an idiot for you."
This close he can see Gokudera's smile falter, can see his eyes go dark with disbelief for a moment. That's all normal too, this shiver of insecurity after Yamamoto says something unexpected. But it will fade, as it always does, gives way instead to crimson embarrassment spreading out over all of Gokudera's skin, and Yamamoto is ready for that too, tightening his hold so when Gokudera snaps, "Idiot" and shoves at his shoulders he isn't dislodged. It's right after that's the best, right when Gokudera's smile reemerges like it's being forced out of him, affection coming soft in his eyes as his resistance gives way, and Yamamoto is already leaning in to taste the soft pleasure of that word on Gokudera's tongue.
Insults are easy to deal with, when Gokudera's actions speak so much louder.