They are realistic, in that their treatment and personalities vary. You will notice that Calpurnia is a disciplined, strict and heavy handed nanny for Scout and Jem. Tom Robinson is a wrongly accused, hard-working and honest fellow. They are diverse in nature yet similar in the treatment that they received from the white community. Calpurnia is half respected half laughed upon and Tom Robinson was almost lynched and was thrown into jail narrowly escaping the death sentence for being falsely accused of raping a girl.