Revenge and hate, this is the main theme that author used to write this story. it felt simple and cliche but still interesting. How cliche is it? MC is orphaned and raised by monster, and it killed by human, so he started to hate human and kill them because of it. What make it interesting is how good the execution is. Its not about "look the MC is going to take revenge and start to killing human," but its about "The MC has killed human, so what is the consequence to that child as human? for being a murderer of the same species?"The MC has killed some human, and the family of the human he killed is trying to chase him too. This is where world building and character development works, and author did not disappoint.