"It must be hot under that mask." Hidan was met with silence as usual. "Why the hell do you keep it on all the time, even in summer?" The hot sun beat down on the two of them, and he was feeling uncomfortable even without a shirt or hat. He could only imagine that Kakuzu must have been boiling. "Why can't you answer me, huh? Did your brain get baked in there?"
Kakuzu didn't turn around but finally spoke, "Secrecy."
"And these Akatsuki cloaks we're wearing blend in so much, right? Come on, that's a stupid reason. Nobody's gonna be less afraid of two men in these uniforms if they see that one of them has stitches. There's nobody around right now either." Hidan didn't get a response that time.
When they were alone in a shitty motel, Kakuzu sometimes removed his masks. When they slept outside, he didn't. The moon had cooled down the air just enough that sleeping would feel natural. The corpse of the bounty they'd captured on Kakuzu's insistence was lying against the tree in-between him and Hidan.
Finding himself bored, Hidan continued his earlier conversation. "It's not like it's good protection… unless you're worried about getting your face scratched." He snickered at the thought. A few scratches would pale in comparison to the huge lines of stitching running along Kakuzu's entire body.
"Are you on that again? Go to sleep." Kakuzu replied gruffly.
Hidan ignored him. "It makes a shitty fashion statement, if that's what you're going for." But that obviously wasn't the case. "And it's not like you're ugly, either."
"…"
"Is that what you're worried about? I bet it is. So you're an insecure teenager now?" Hidan knew that it wasn't true, but he felt like teasing Kakuzu anyway.
"Shut up and go to sleep."
They killed another shinobi the next day. He proved to be skilled and a worthy sacrifice to Jashin. Kakuzu wore his real face from the start of the fight and didn't hide it again even after their opponent died. That was probably to avoid listening to Hidan complain about it again.