Prologue.
Kasuga made a mistake, Sasuke knows this and Sasuke worships this. You never fall in love with those you are sworn to protect. Didn't she know that was the first the rule? Because, in the end, the final duty of a Shinobi, when their Master falls, is to become them. Love would interfere with that, would it not? How can you do your duty if you are so distracted. He tells her this and she laughs in his face. Love makes you stronger, not weaker, she says.
Sasuke scoffs at her but sometimes his eyes linger a bit too long on Yukimura.
But he knew the first rule. Still, there are nights when Yukimura comes to him, burning hot and he's ready to burn Sasuke. Sasuke takes all his master gives him and on these nights, titles and names merge and Sasuke doesn't know what to call Yukimura in the morning.
Even still, Sasuke doesn't let it show, "Can't get enough, danna?" it's husky and Yukimura blushes. Sasuke thinks he likes less red on his clothes and more straight on his skin.
It starts with curiosity and Sasuke is always willing to show Yukimura just where to touch and he never once questions why. Yukimura is embarrassed at first, nearly always. Sasuke just lets it happen and Yukimura is a fire. He'll lose control soon enough and Sasuke wants to get burned. He tightens his leg around Yukimura's hip and his head is tossed back. His skin sticks to the floor and his cock pulses against Yukimura's stomach. He lets Yukimura set the pace because Sasuke is a Shinobi and Yukimura is the master.
Sasuke knows better than to fall in love but when Yukimura reaches for his hand and kisses him he wonders if he is maybe it's too late. He wonders if maybe Kasuga is right after all.