In the long river of time, we are all prisoners. The linear law is like an invisible shackle, nailing every life to a one-way execution rack, destined to trek towards the destination from birth.
And what "The Sky Mender Sequence" is about is a thousand-year agreement to fight against this fate.
There is no myth of immortality here, only "consciousness programs" encoded in the folds of time and space - that is the contract carved by the guardians with their lives. They have long since turned into stardust, but they have cast their obsession with guardianship into an automatically triggered command: whenever the protected thing encounters a disaster in the long river of time, this program will wake up at the most logical time and space node, looking for a "carrier" to take root.
It could be a soldier holding a spear in the flames of the Warring States Period, whose eyes suddenly flashed with determination that was not his own; it could be a painter working in a Renaissance studio, a symbol that spans thousands of years unexpectedly appears on the canvas. The carriers are different, and the past is forgotten. Only the core instructions are like immortal sparks, igniting the same responsibility in every body.
Individuals will eventually be annihilated, but the "relationship" and "responsibility" defined by the contract weave an immortal circuit in time and space.
When the physical laws of the universe are as cold as iron, and when the death and birth of all things follow unquestionable formulas, human beings must use the glimmer of consciousness, the temperature of emotion, and the weight of belief to open a crack in absolute necessity. It is an enclave ruled by "meaning" and "choice". It is small, but it is enough to resist the eternal nothingness.
Open the "Sequence of Menders" and you will find your own answer.