The Secret Sea

Julia's body is first taken over in this episode, bringing the sibling god's together for the first time in over a millennium. Eliot, who's body is taken over by the monster and Julia, who's body is taken over by the monsters sister, are loosely based (according to Lev Grossman, the author of the book trilogy the show is based on) on the characters of Lord Sebastian Flyte and Lady Julia Flyte from the book, Brideshead Revisited by Evelyn Waugh, who are siblings, like the two gods are.

When Josh is turned into a goldfish, Margo refers to him as "Nemo" - from Finding Nemo (2003) - except that Nemo was a clown fish with red and white stripes.

References Finding Nemo (2003)