Victor Frankenstein’s girl — fiancee, cousin, whatever she’s called — is a non-entity. She’s fridged! She basically dies so that Victor can feel something. Her arc is incidental.
Frederick’s girl is a whole ‘nother matter. Go Madeline!
She’s fussy. “Taffeta, darling.” Precise, prissy. Appearances, order, decorum, are all important to her. Partly she’s portrayed as uptight because it gives her an arc, a very funny one. Also, she represents society and civilization to Frederick. His arc is to leave all that behind and embrace his wild ancestor side. Although her character is stylized as a comedic tool, Kahn crafts all this into a true portrayal.
Like Frederick, she also is set free by the end: she loves the Monster. He, reversing our expectations, becomes civilized. This Elizabeth has it all. Order, social appearance, dignity on the outside. Passion on the inside.
The Monster, with half of Frederick’s brain, becomes the Seven that can live in society without losing his wildness. (Frederick becomes a Seven who lives in the wild while holding onto some semblance of society.) This is the version of the man that suits Elizabeth best.
Passion on the quiet, dignity on the outside? Five.