I'm writing a Halloween AU and it's fantastic I'm super excited about it but here's some of the things that inspired it:

Half-blood Vampire Leo (that's a long story)

And Braken as a sort of merman thing ... mostly inspired by the mermaid Braken SingACh0rus posted in his art book (go check it out it's awesome)

Those scales might've killed me.

And I have yet to draw Joel as a werewolf ...