Your fantroll having black hair depends on their caste. if they are from a higher caste ( particularly purple or vio.let, which i will explain why later)
they most likely will dye part of their hair their caste color.
(the only reason i didnt include fuschia bloods is because i have a headcanon that there can ONLY be 2 fuschia bloods in all of alternia, the heiress and the empress.(in this case feferi & the condesce))

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