You don't need the fairy tales for any ending.
Spawn where? For the end of his quest, you have to beat Jub jub, Bandersnatch, and Jabberwock with his help. It's possible to mess up if you find him in carrol river but forget to go back for him after beast of conceit.thats what i thought too but i tried doing that and vernai did not spawn and i dont know why
so i had to restart