Other angels, some demons. When I say old I really do mean old, hundreds of thousands of years. There are certain sigils that can mask a person from an angel, in our language.

[ She's sure that there can't be anyone else here who knows about these things, other than the people from her world, and none of them would have any reason to hide a person from each other. ]

You'd be hard put to find anything other than beings who have lived as long as me who know these things any more.