I actually had the heroine thinking the legends of fairy ointment and humans who lost an eye by admitting that they could see the Fair Folk in that eye. . . at the same time that someone was singing "Tam Lin."
Which ends, of course, with the Fairy Queen saying she should have torn out Tam Lin's eyes.
sigh. Heroine's going to have to reflect on that. Because she may be in danger of losing her own eyes at one point, and she knows it.