" Stars, that hand gets cold,” Kai murmured. Rolling onto his back, he took the prosthetic hand in between both of his palms, warming it as he would warm icy fingers on a winter’s day. Cinder sat up and looked down at him. His eyes were still closed. He could have fallen asleep again, but for his palms rubbing over her metal hand. His shirt was rumpled, his hair tousled against the sheets.
“Kai?”
He grunted in response.
“I love you.”
A sleepy smile curved across his mouth. “I love you too.”
“Good.” Leaning over, she kissed him fast. “Because I’m taking the shower first. "

― Marissa Meyer , Stars Above (The Lunar Chronicles, #4.5)