I think it's very, very messy, you don't have half of Moon yet, but I'm already putting the first timeline. So you can start visualizing the time. I will always be open to questions!
In a bygone past, before the truce and saving Nigthmare, when the universe was still trapped in darkness. The hero had to find a way to awaken Daylight and end the reign of slime at the same time.
Although the player will be able to choose, in reality the hero really seeks to save this universe, he first made a defensive Run which ended in the exhaustion and death of Daylight. Second Run aggressive towards the mucus which then ended with the Bloom form of Daylight.
The latter having exhausted all his light to absorb the darkness to try to help the Hero. He defeated Moonnight, and lost control after destroying it. You should know that before the true ending which even in the present, the hero did not know that Moonnight was actually Daylight's brother. After the catastrophic route, it will be forced to reset by Daylight.
As each of the neutral runs will end in death and the end of all hope, the hero will end up asking to save EVERYONE when he releases Daylight from his stone prison. This will be the most difficult road for him, because he will only defend himself and ask Daylight not to defend him.
After this one which gives the true ending and lifts a lot of secrets, he will no longer use his power. Even in the present day Daylight has a faint memory of the run where he killed his brother. He is frightened of it, and sometimes locks himself in his palace for a week or two, covering all the mirrors.
Astratale : PAST STATUE FORM DAYLIGHT ( Shade for this ref)
The moment everything changed. Don't be fooled by the adult size. He is a child, a poor child who sacrifice his life for the light of this world. When it was recognized that he had the gift of light, Daylight was the happiest in the world. Being part of the light lenders to enlighten the world was the best thing that ever happened to him.
Not only was he helping others, but he and his brother were pulling insecurity out of the darkness. Unfortunately any priest of light must accept the reality, their lives are accelerating and will remain forever shorter than the others. They age faster at the height of their gift. This is why Day, despite being the same age as his twin, will reach his adult form a few years later.
It was a well-kept secret, only the priests knew about it. And their loved ones had to accept it. But how could Moon accept such a thing? To see him sacrifice himself for a miserly world of darkness instead of staying with it. He doesn't have the gift, he couldn't save Day, so he searched... searched...
In the old books which were still more or less intact from the time after the iron fall. He found something, a text on dark magic. He didn't quite understand it, but he wanted to try... And everything went wrong.
His body had been frozen for a millennium, and his conscious mind sensed his brother's desperation laughing in his savagery, to forget he was.
But in the end, his brother saved him by statifying him. His energy returned to him, and Moon protected him from his own madness.
Day is just waiting to save his brother, but he lets the hero choose how he will use his magic. It is a pact of trust by the trait of soul of the hero...
His first uniform, after being selected as a light-reader, Day knew that now their lives with her brother would be better. Even if Moon didn't have his gift, he would immediately be taken out of harm's way and pulled from the streets with him.
A dream that was to come true, save his brother and help the world... He will learn shortly later that his power will cost him his years of life. But he will continue, his body will age rapidly making a strange gap towards his twin.
Once he reached adult height when he was just a child, his bones began to have the black mark of the limit of his body. Basically he was terrified of death but could no longer hide from the expectations of others....