How does Aaron fit in?

Revenge seems to overshadow Regret in Titus Andronicus and the other plays we have been reading, however Aaron does not even have a compelling motivation such as Revenge. Not only does he not show any feelings of remorse for what he has done, his only disappointment comes from his inability to further wreak havoc amongst the people in Rome. Aaron's character stands out as unnaturally cruel even in comparison to the selfish murderers and rapists. In this passage the reader sees Aaron invent new ways to manifest his evil. Does Shakespeare intends for Aaron to be the epitome of human sinfulness? Does his race relate to the nature of his character? Judging by the way the text describes his child as being evil because of the son's skin color, I would be willing to apply the same circumstance to Aaron. The easy way to explain why Aaron's character seems so unmitigatedly cruel is to attribute his nature to his skin color, but I don't feel inclined to view this characterization as an overtly racial decision on the part of the writer. Aaron is one of the only characters who prospers in the end of the play, I think he symbolizes evil itself and lives to show that life is cruel and unforgiving. Aaron lives because there is not justice in the world, and injustice has been the prominent theme within this play.