He follows Hermione

Hermione had sat down in the library as Harry sneaked up behind her, considering what to do next. Maybe it was a good chance to give the ray gun itself a good try and so he aimed at Hermione. A quick blast of the gun hit her head and within moments, her hair had started to get blonde again. A loud moan escaped Hermione's mouth as her hands moved down to her crotch.

Soon she was masturbating in the corner of the library, still haven't spotted Harry, who was happy how well the ray gun had worked.

"Hey, Hermione," he said and she spun around, fingers in her pussy, panties around her knees. "How are you?"

"So horny," she moaned as she crawled over and quickly got his cock out of his pants, starting to suck before Harry could say more.