I remember a book (all text) about a boy that died (perhaps in a train accident) and woke up in a weird afterlife.
Someone "printed" a calendar on his arm to remind him of a date when he will have to decide to either follow the weird man in what was supposed to be a paradise, or to stay in some sort of wilderness with some other people (I remember them as kind of rebel). I also remember they have a some sort of flying animals, I believe.
I think that in the end he choose to stay with the people and just fly around. Perhaps there is a sort of magic that allows him to see what happened on Earth when he flies with the animal... With this specific animal, he will dive in a sort of infinite ravine, where he fly into the cloud, to see what's happening on earth, until the animal is too tired. The boy is alway trying to get deeper into the ravine.
In my memories, the whole story happend on flying island, but honestly it could be my mind tricking me.
I read this book around 2010 in France, I don't know if it have been translated from or to English, and I don't think it's a saga, only a single book.