According to Leo himself, he has been analyzing the show for roughly about a year and a half and he sees so much wasted potential.
he plans to use that "wasted potential" and instead of altering big canon events of CS like he planned (The Canon Ending for example) he chooses to subtly change parts of the story to add his OC, AND add to the already interesting plot of CS
since the showrunners of CS were careful to tread on certain topics because of the fact that it is a kids show, the parts of the story that were meant to hit hard felt melancholic and bland.
Leo, however, has the freedom to deal with said certain topics and he chooses to do so! and for what he has told me about his S1 and S2 alterations, he really connected allot of the dots that scratched my brain. STRONG EMPHASIS ON CRACKLE IN SEASON 1 (i'm unable to talk about specifics as i promised Leo i wouldn't be spoiling his AU so bear with me :'>)
to sum it all up, i think Leo's way of writing his AU is closely accurate to what the show wants to portray AND is even delved into in such a way that it feels more alive
KEEP GOING @leo-illustrations U GOT THIS