maybe coverup magic or sum i cant even rebember the plot
Some sort of genetic thing. Happens all the time to children. Children born of brown/blonde hair would grow up to have black/brown hair. I watched it happen to my little brother as he grew up. He used to have brown tufts of hair as a baby but now it's black.
Honestly, only way I could explain it.
I was born with jet black hair. By the age of 4 it was platinum blonde, which gradually darkened over the years, but now it's going silver (or "sparkles" as I like to call it)
So I'm guessing Kian and Cain are the same person? They both have blue eyes...but the hair is different.....