Ah ha. There was one. Luna could feel it by her ear. She turned around to hit it away and found herself face to face with a girl.
"Oh! Sorry about that," Luna said, startled. Her eyebrows shot up so her permanently surprised look looked comically surprised at that moment.
The girl surveyed Luna with interest. She had dark brown hair and a blank expression. She did not look angry or even shocked. The girl looked almost as if she had been expecting it. Luna surveyed the girl's robes. Blue. That meant the girl was in Ravenclaw- same as Luna's. Luna peered at the girl.
"You're not in any of my classes are you? I think I would've seen you."
The girl shook her head. "In my fourth year. You're in fifth." How did she know that?
Luna vaguely smiled at the girl. "I'm Luna."
The girl cocked her head. "Luna. Latin. Means moon. The goddess of the moon in Roman mythology." The girl stared at Luna for a few seconds before saying, "I'm River. What was the strange motion you were doing before?"
"Whacking a wrackspurt of course," Luna replied calmly.
River's eyebrows shot up in interest. "A wrackspurt? What are they?"
"Oh they're invisible creatures that like to fly by people's ears and make their brains go fuzzy."
"Brains go fuzzy," River repeated. She then looked confused. "If they're invisible, how did you know where to hit it?"
"I didn't," Luna said disappointedly. "You can see them with Spectrespecs, of course, but I forgot to bring them with me."
"Can you show me?" River inquired interestedly. "I am curious as to what wrackspurts look like."
Luna smiled at River. She nodded and the two of them walked off together, chatting about wrackspurts and Crumple-Horned Snorkacks.