"So it's possible to make a copy of people from my world. But obviously making a copy of someone isn't a very nice thing to do, so the Valar decided to change that. And a long time ago - a thousand, four hundred years ago - they did magic to make us uncopyable.
And then recently there was a horrible disaster somewhere. And they found the place with the magic door, and they knew my world's gods were good at their jobs and would help, and they needed someone from my world to open the magic door so they could go get my gods for help. And they tried copying me, but it didn't work because of the magic.
So then they tried copying me-before-I-was-made-uncopyable. And that's how I - came into existence. And it turned out that in the - years I missed - I had gotten married and had children."