Jon had decided that it was better at the moment to lie and explain later if she found out the truth than to deal with how she would act, possibly violently, if she was told the truth right off the bat. The mermaid kept her beautiful blue eyes on him while he prepared himself, in both his body language and his speech, to convince her that what he was about to say was the truth. That focused gaze convinced him that body language was going to be just as important or more important than what he said.
"Where you are? Well, as you can see, you are in my room," he said rather plainly and motioned to his surroundings after he had stood back up. She couldn't really gather any information from what she saw since she didn't know too much about humans and their world. If she had known anything about sports, some of the memorabilia scattered around the room wouldn't have made much sense in terms of geography. He had a Texas Rangers logo on one wall, an Orlando Magic jersey in his opened closet, a New England Patriots logo on his closed laptop, a Vancouver Canucks shirt next to the aforementioned jersey, and a Los Angeles Galaxy logo on a soccer ball.
"Now as for how you got here... I was going to ask you the same thing. I had assumed you had used some kind of teleportation spell and messed up your destination," he said, showing he was also a sci-fi/fantasy nerd and not just a sports geek. At this point, he really hoped that there were similar stories of magic where she came from. He simply figured that since she was a previously thought mythical being that some sort of magic, besides the stone, must exist as well.
"Of course not! I've never used magic. It just leads to lazy mermaids and flabby tails," she responded, confirming his assumption. "You have enough knowledge about magic to know about the existence of such spells. How do I know it wasn't you who brought me here with such an incantation?," she asked, trying to be threatening, but it wasn't easy to do when she couldn't raise herself off the floor much thanks to the lack of a knee in her tail.
"Just because I have the knowledge, doesn't mean I have the means. You know about humans walking, but that doesn't mean you can as well," he answered, motioning toward her tail as her caudal fin continued to flop against the floor in what seemed to be an involuntarily action. He smirked, thinking and hoping that he had proven a point. "Well, since you didn't cast a spell and I certainly didn't bring you here, maybe you slipped through some sort of portal," he added, hoping to end the debate about how she got there.
She looked as if she was going to respond angrily to that, but she stopped before any words came out. She seemed to be considering it in her mind before she finally spoke. "You may be right... I didn't see anything when I was swimming, though," she said, still unsure. "I'll trust you, for now... Since I don't have much of a choice," she concluded, apparently convinced for the time being, both by his speech and especially by his body language. "No matter how I got here, I'm going to need your help to get back home," she said, looking up at him again. "Or at least get me into some water soon..."
((Author's Note: The teams in this episode were chosen to both keep the vagueness of Jon's location in terms of state/nation, though clearly North America, and add some detail to the room.))