"The search for power begins when we're quite young. As children, we're taught that the power of good triumphs over the power of evil."
"But as we get older, we realize that nothing is ever that simple. Traces of evil always remain..."
trace: a mark, an object or a sign that shows that sb/sth existed or was present
evil: the force of things that are morally bad
remain: to still be present after the other parts have been removed, used, etc.; to continue to exist