"My name is Kismet, and I'm a kitsune."
Thomas felt the words wash over her, their directionlessness nature soothing her not just frayed but falling apart nerves. She moved her mouth to speak, but the voice... Kismet... seemed to anticipate the question.
"A kitsune is a kind of fox spirit. The short version of the story is that I had been sealed in that medallion, and when you put it on, I got moved from it into you."
Thomas's throat clenched. A lifetime of being the quiet, capable, intelligent one out of every crowd hadn't prepared him... her... for this in the least. "...bwa?"
An ethereal sigh at the edge of hearing rippled the air. The kitsune, whatever that was, spoke slightly more slowly than before. "What I am telling you," said Kismet, "is that we are sharing the same body and that is why you look like you do. However, it doesn't have to stay like this. And you don't have to reply vocally, since we're in the same head I can read your thoughts."
Thomas could actually feel her ears stand straight up at the prospect of recovery. She opened her mouth, shut it, opened it again and shut it with some sense of finality. She was, after all, more at home with the subtle inflections of body language than speech. Hopefully... telepathy wouldn't be too much different. How? She felt slightly dismayed that she couldn't have her old voice, even inside her own head.
"You're probably wondering why I was sealed in that medallion," said Kismet to Thomas, who hadn't been. Being sealed up, as far as he knew, was an activity that magical fox spirits undertook at regular intervals. "I can see that you know a little about dragons... unicorns... phoenixes... werewolves... all sorts of creatures you call mythological." There was a pause, and Thomas was aware of a rummaging sensation moving through his head, tossing up random memories into his forebrain as the presence searched around. The effect was rather like what he imagined a dose of LSD must be like, except he didn't have any fun and didn't get confused about anything.
When finished, the spirit fox continued in a slightly annoyed tone of voice. "Nothing about kitsunes, however. Anyway, a long time ago, the magical community detected something like... like an ice age for magic approaching. The magic would dry up and any creature that depended on it would go belly up. Those of us who could grabbed what magic we could and sealed ourselves away until it was over. And it's over now, but so much magic was sealed within our self-imposed prisons that it's really weak here in the outside world. I can sense it. There's not nearly enough to make a new body for me to inhabit."
Thomas, who had been taking this stoically, blinked her eyes slowly. You want us to do what now?
And the kitsune who shared her head replied, very firmly, "Let's go free some monsters."