Let’s go back to the original Dracula novel. You probably know that many liberties have been taken with Bram Stoker’s Dracula novel over the years (due largely to the success of the 1931 film which embedded several changes into the public consciousness), but every now and then, you have to stop and appreciate just how different the original novel is from what we typically think of when we think of the Dracula story.
So how much were the brides changed in the many Dracula films? Well, Dracula’s brides were in the book and, for the most part, they were portrayed similarly to how you’d probably imagine them if you picture them in your head when you think of the various Dracula adaptations in pop culture history. They’re highly sexual, they live in the castle, and they’re vampires who seem to be somewhat subservient to Dracula either because they were turned into vampires by him or they are his actual brides.
What’s interesting, though, is that the Dracula novel never actually references any formal relationship the characters have to Dracula. It’s never explicitly stated that they’re married or that they have some kind of relationship outside of being vampires. In fact, the only time that any such relationship possibilities are referenced is when they’re described as “weird sisters.”
Now, it’s possible that the term sisters is just an example of the colloquialism of the time. Mina calls Lucy her sister at one point in the story, and the vampires call Mina their “sister” after she drinks Dracula’s blood. There’s certainly enough evidence to suggest that the term “sisters” is being used rather casually. That last example even suggests that the trio see themselves as sisters because they were all turned into vampires by Dracula.
Before you entirely disregard the theory that the “brides” are actually sisters, though, consider their original physical descriptions. Two of the brides have dark hair and are specifically described as resembling Dracula. However, the third bride has blonde hair and is treated differently from the other two. She’s addressed by the other brides with a kind of reverence, and her tomb is more elaborate than the others. Even Dracula seems to treat her with more respect.