Just imagine his Daily life and write in first person. He is the stable buck meaning he does a lot of menial tasks and because he is black he gets a lot of verbal abuse from the other men. Write about his tasks e.g. "I got up before dawn today. I was the only one awake, even the birds were still asleep, and it was nice to be alone in the stillness. No one to yell at me, no one to shout and insult me. But of course that didn't last. Once I had finished harnessing the horses..." Perhaps you could make the writing style closer to how he talks as well.