I am confused....

So am I missing the point here? I am really confused after reading Shadow Slave. Is Sunny the MC? or is Nephis the real MC? Is the novel kind of like a Sherlock Holmes situation, where Watson is the narrator and Sherlock is the protagonist ? Because Sunny really feels more like a side character throughout the story and less interesting imo when compared to Nephis. Also, does he ever stop being a slave to Nephis? I know the story is called Shadow Slave but still...