(Author's note - Athena didn't hear the wish, even if Sarah did.)
When the light was gone, Sarah looked down at herself in shock. She was in Athena's body! "Ugh, I'm a freak!" Sarah yelled out in disgust. It was weird for her to hear Athena's voice instead of her own.
Athena, who was in Sarah's body, stood up. She was also disgusted. "Why'd you bump into me, you freak?! If I get some sort of weird disease, I'm blaming you..."
This was a case when Jon's "precautionary" wish came in handy. Even though he wasn't in hearing range of Sarah's unfortunate wish, his memories didn't get altered and he still remembered how things were supposed to be.
