One thing I really loved doing for my novel was exploring the relationship of Coco and Miguel.
Canonwise we know that they've been very close. Giving that Coco took after her father so much, loving music and having it in her soul, it was easy for her and Miguel to connect, because he too takes after Héctor most of all in the family.
We know Coco always used to sing to Miguel and in the movie we see Miguel hanging around Coco the most. Even after Coco couldn't really interact with him as much as she used to because of her age, she still went along with all his quirks and games and listened eagerly to whatever he told her.
Their relationship is just so pure and sweet and I loved writing it. All the while remembering my own grandmothers whom I'd been very close with.