He remembered Orpheus, who made a deal with Hades to get Eurydice back, as long as he doesn't look back until he is in the mortal world. Orpheus, who grew impatient and turned to look back at Eurydice, sending her back to the Underworld. He never understood the man's impatience until now. (A retelling of the story of Andrew Blackthorn and Lady Nerissa in Julian Blackthorn and Emma Carstairs.)