They sat down at the restaurant--Erin had dried off so she wasn't dripping anymore--and ordered dinner. Erin had the sushi, which she explained she'd developed an affinity for following her change of shape.
"Speaking of that," John began, curious, "can you tell me about it?"
"I suppose I should start off with exactly how this works," she said, pointing down. "It's not bad really except for stairs, not being able to drive a normal car, and whatnot. Luckily I don't have to keep myself wet or anything." She laughed a little. "I can swim a lot better though--it only took me about ten minutes to get up the beach to your place. And apparently I can breathe water. All in all I'm pretty happy with this, honestly. Oh, and I should probably mention..." She leaned in close and said quietly: "Things got a little rearranged, but I still kept...you know..."
Before John could get a word in, she leaned back in her chair and continued. "So, how did I end up like this...well, my grandma was a full-blown witch, and I got to rummaging through her books after she passed away about ten years ago. I read the first spell I came to out loud, and the next thing I know, I woke up with a tail. Dad told me he could reverse it--he knew all of granny's tricks--but I wanted to try it out. Not every day you get to be a mermaid. After a few weeks I decided to stay like this and dad worked up a selective memory spell that means people will only notice I'm not perfectly normal when I want them to."