An ultimately test of the self versus the selfless:
Suppose we have a character, I'll name them Sam, suppose Sam was a created person. An AI, an Android, a clone, an engineered test-tube creation, whatever they are they have to be artificial. Now suppose that they were created to fulfill a specifically violent role on behalf of their creator. An enforcer, a hunter, an interrogator, etc. Furthermore, because their creator is not a heartless bastard, they made sure that their creation, (Sam), would find fulfillment, contentment, satisfaction, and joy in that role. So Sam is a sadist of the highest order that genuinely enjoys violence and causing pain, but not in a malicious way. They enjoy it in the same way that a child enjoys jumping into a heaping pile of leaves, or you or I might enjoy the sight of a beautiful sunset. Their enjoyment of their role is not in any way perverse. Rather, it is the most natural thing in the world for them. The satisfaction Sam feels in gruesome murder is comparable to the satisfaction you or I feel when drinking a cold glass of water after a long, hot day.
Now suppose that Sam is fundamentally innocent. They do not understand the consequences of their violence, or even the concept of evil. They do what they do because it's what they were told to do by their creator, because it's their purpose, and because they find genuine fulfillment in embodying that role. Sam is a like a child, or more like a particularly violent golden retriever that constantly tries to show you its love and affection by "retrieving" the neighbor's pet cats.
Now suppose that they exposed to enlightenment. Something expands their consciousness, catalyzes change in their being, or else let's them see the world for more of what it truly is. They come to understand the meaning of evil, and that evil is what they are. [2:08 PM] . Sam rebels, they leave their creator behind and run away, either on their own or with the help of the creator's enemies, and they try to change their life around and do what's good.
There are several obvious conflicts to resolve, their relationship with the creator, their lack of empathy, the absence of life skills not relating to horrific torture and murder, but there is one thing that rises above the rest. There is an existential battle here between nature and choice. Sam's nature has not changed, they still find satisfaction and fulfillment in acts of profound evil, they just choose to deny it. Sam will spend the rest of their life knowing their purpose, their calling, their "dream job" to spend the rest of their life doing, and they will spend every second of that life running as far away from as they can.