Something something the crawlers are all both Orpheus and Eurydice. Orpheus's skill as a musician what lets him travel the underworld despite the danger. The crawlers needing to be entertaining to help them survive the dungeon. Carl is helped by past crawlers who looked back because they couldn't ever leave the underworld. Carl looks back to the people he couldn't help all the time, and that anger but more importantly that love keeps his going. The crawlers taking deals at the end of the ninth floor look back in love, and pass on their strengths and skills for their Eurydices' before they descend deeper into the underworld. Li Jun looking back before he sacrifices himself to thank Carl for the extra time with his sister and best friend. Katia almost being destroyed by the Blitz Sticks that let her look back upon Annie, and going through detox with a friend to witness that memory with her. Carl learning about a brother he never knew existed and taking a moment to mourn him instead of seeing his father die. Choosing love over and over again.
"Dying a second time, now, there was no complaint to her husband (what, then, could she complain of, except that she had been loved?). She spoke a last ‘farewell’ that, now, scarcely reached his ears, and turned again towards that same place."
-Ovid, The Metamorphoses