@melian6 Yes what you said is true
Spoiler!
Eirin is basically the Goddess of this world. This world's story is written by Cha mi soo when she was younger. She wrote this story as well as other stories which turned into different worlds and the children who are basically treated like unwanted and unhappy in their family go to this world.
You noticed a small black haired girl with multiple drawings was seen in the start of this season near a cog wheel that girl is actually Cha mi soo younger self. So yes she is the G** of this world.
So at the end of the story Lucilion becomes half immortal just to accompany Eirin as she will love for a long time and Eirin asks her father to become immortal as well because then they will be together. But he refuses and says that he doesn't want to because he wants to be with his wife after his death. So Eirin agrees and says that it's okay at least now they have a lot of time to spend before he becomes old☺️
You noticed a small black haired girl with multiple drawings was seen in the start of this season near a cog wheel that girl is actually Cha mi soo younger self. So yes she is the G** of this world.
So at the end of the story Lucilion becomes half immortal just to accompany Eirin as she will love for a long time and Eirin asks her father to become immortal as well because then they will be together. But he refuses and says that he doesn't want to because he wants to be with his wife after his death. So Eirin agrees and says that it's okay at least now they have a lot of time to spend before he becomes old☺️
I like to post spoilers for the stories I find interesting because I don't have much time to read novel due to busy schedule
you will find me in most romantic historical manhwa comment sections 
you will find me in most romantic historical manhwa comment sections