Well, first of all The Color Purple falls under the broadest genre of fiction. The three primary genres are poetry, drama, and fiction.
Hair color is determined by two different forms of pigment: eumelanin (which is the largest influence) and phenomelanin. Eumelanin is a black pigment, and phenomelanin is a red or yellow pigment. Hair color is determined by three factors having to do with pigments: how much pigment is present, to what degree a eumelanin or phenomelanin is present and how close together the melanin (pigment) granules are. The more eumelanin a person has, the darker his hair will be.
This will help you determine how your hair will react to certain colors. If your hair was a warmer color (honey blonde or similar), your hair will likely react with a warmer color now. Similarly, if your hair was a cooler color (ash blonde, brunette), your hair will likely have cooler undertones when you dye it now.