"... and that's adrenalin," Junhong finished his explanation, looking up at Youngjae with a hopeful expression, but the older just sighed, shaking his head.

"Not adrenalin, Junhong."

The boy frowned, looking down at his notes again and flipping back a page before facepalming.

"Oh, right. Serotonin," he corrected himself shyly and the older smiled.

"Exactly, serotonin. What's that again?"

"Um..." Junhong blinked before smiling at his hyung. "It's what makes me love you more than anything else."