( This... is going to take some explaining. The truth might sound like a tale of the fantastical but honesty is probably the best policy. )

No doubt this is going to be very strange to hear but we know one another. I know you when you're older than you are now. We're acquaintances. ( The word is chosen in case it might spark some memory. ) We found ourselves away from home, on a journey. We travel to different islands to learn about ourselves. This is one of those islands.

( Too much at once? Not enough? If he's anything like his adult self, he'll probably be quick in telling her either way. But the fact he's so young, seems almost vulnerable, makes her cautious. )