“What are the chances you’d ever meet someone like that? he wondered. Someone you could love forever, someone who would forever love you back? And what did you do when that person was born half a world away? The math seemed impossible.”  ― Rainbow Rowell, Eleanor & Park   Kyuhyun knew that

Kyuhyun doesn't know or care about when the nicknames started. Ryeowook remembers for both of them.