So, at the end of the story, there is this golden dragon and Penelope and the others have to fight it, and it was about to kill Penelope and Eclise jumped in front and saved Penelope from the blow. Later, they are looking for his body and it cannot be found. (He is alive!!🤩) And he goes pretty classic, but pitiful yandere, like he wants to take Penelope away and is really manipulated by Yvonne and betrays Penelope in the name of Penelope, so that is the only reason I was annoyed with him really.
And the Duke.. There is a lot that goes down with him. (I'm assuming we are talking about the actual duke, not Derrick.) So, he really does start to try to be a better father to her, but you know, to little to late. One example is on the morning of Penelope's coming of age ceremony, at one point she had asked him to visit her on the morning of. But at this point, she was actually planning on commiting suicide, and was going to take a poison. Before she took it though, the duke visited her, and they had a very sweet conversation. She didn't commit suicide, no one really knew that she was going to, but stuff goes down at the coming of age ceremony. I suggest that you look through the spoiler forum,
https://forum.novelupdates.com/threads/death-is-the-only-ending-for-the-villain.97486/ and look for posts by Elyriona, she pretty much translated most of the novel there.