Responses

I mean it's classed as side stories because it's tying up loose ends. For example, we was told Hye had a really tough childhood but it was never explained or given a broader view in the main plot because it just wouldn't have fit. Therefore they are using the side story to explain how that trauma has effected Hye and giving us more insight in what happened for him to act the way he did at the start of the book.
The way the side stories are piling up, this doesn't feel like side stories anymore, more like just another season