Having finished the series "Remembrance of the Earth's Past" by Liu Cixin (author of the Three Body Problem - on which the recent TV series was based) - I noticed in my library's app that there was another instalment in the series, but ... by another author.
Usually this happens when people die before they finish something, or they want someone just as clever to help them with the story, technical details, or other bits and pieces.
In this case, The Redemption of Time, as per the forward in the unabridged text, took the form of fan fiction, which was later expanded then translated, and has now become a "part" of the series, building upon the world which Liu Cixin created.
Instead of carving out entirely new ground, this (much shorter) tale examines the untold stories of several characters throughout the timeline of the original series, and adds incredible depth and humanity to a story that was otherwise - a lot of exposition.
It enriches, but doens't approach the greatness of Cixin's work. There's some profound, incredibly complex stuff about the various dimensions of the universe (with this book proposing that ten dimensions - that collapse downward into a single dimension (of ontological space) - being the most ordered form of the universe, where time... doesn't exist.
It proposes that time is the gap between these dimensions, in some round about way, and it is fascinating, but in the end, just science fiction.
It builds some interesting points, and there are a few scenes that I will (fictionally) remember for quite some time, as there's emotional impact wrapped up in the narrative - but ultimately, this is fan fiction, made official.
It has some shining highlights, but like all matter in the universe, and much like grief for something that is over, this book lengthens the period of time before you have to accept that something wonderful is over.
And that, in and of itself, is something wonderful, too.