Genya doesn't know if he likes you or not. You're Gyomei's other apprentice so he always feels like he has to compete with you. You're as sweet as can be yet he can't allow himself to be anything but cold to you...

He thought it was over for him when you saw his demon features. He figured you either try to kill him or be so disgusted that you'd never speak to him again. Instead, you helped calm him down with a gentle smile and a soft touch. You two became pretty much inseparable after that.