In doll form, a succubun’s hair is equivalent to their bun form’s coat of fur. It can have any texture that real human hair can have, regardless of the texture of the bun’s fur. It can be buzzed close to the head, or grown out as long as ankle length, but it cannot exceed the mass of the doll's body.
The color of a doll’s hair should reflect the bun’s coat. Please review the Bun Fur page for related rules.
Multiple Coat Colors
In the case that a bun’s coat is broken up into different colors, the hair should correspond to the color(s) at the top of the bun’s head. Long hair can incorporate the bun’s body colors towards the ends.
Markings on the bun's forehead or a small tuft of differently-colored fur can be reflected as streaks in the doll's hair. Please note that hair cannot have markings, only streaks and gradients.
Different Hair Color
If you want to give a doll hair that’s a different color from their ears, the best way to do so is to make the bun's ears and coat different colors, so that the doll's hair color matches the bun's main coat color.
In this example, making the coat blue with pink ears, rather than making the entire coat pink with just a bit of blue at the top, allows for the doll's hair to be blue no matter what length it is.
If you want to give a doll a certain hair color, but don't want to make that their main coat color, you can add some of that color to the top of the bun's head. However, this leads to a more complicated and subjective set of guidelines.
The doll’s hair color must still be a prominent part of the bun’s design. You cannot give a doll a hair color that isn’t present on the bun, or that is only present in a tiny amount.
This idea scales up based on the amount of hair the doll has. Since the doll and bun are two variations of the same design, they should have the same palette and color proportions as each other. 
It's important to remember the main intent of the rules for doll hair colors: the hair color is meant to represent the bun's coat in doll form. Real-world rules about hair color and growth do not apply.
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