Via a trigger

Jaune Arc had recently watched videos on hypnosis online and was eager to test them. Each night he managed to sneak into the RWBY dorm and place a radio playing subliminal messages under each girl's bed.

He decided to now test the messages to see if they truly worked.

Making his way to the dorm, he found only Blake Belladonna sitting on her bed. She saw him and eyed him with suspicion.

"What do you want, Arc?" she asked.

"Nothing," Jaune said. "Just thought it was...sleepy time!"

Blake immediately snapped to attention, standing blankly with her eyes glazed over slightly. The subliminals worked, Blake was his until he woke her.