Theory: The Dark Star became the Void.

So, we know that the aspects and celestials of Targon fought against the Void and won temporarily. We know that the void pops up spontaneously all around Runeterra, but as of now, it's only relevant spawning location seems to be Icathia or around Shiruma. (Feel free to correct me.)

So what if, the Void was originally the Dark Star and after being defeated, it downgraded to the void? Think about it, both the void and dark star seek to consume everything. Also, the Darkin is an alien race that came to Runeterra and they speak of being betrayed... Necrit already had a theory that they may have been trying to warn everyone of the void, but ended up being betrayed due to fear.

So, what if the Darkin were trying to warn everyone of the dark star and the targonians feared that people understanding it's existence might come to seek it out for selfish reasons and therefore felt the darkin had to be silenced... It could get spicier. What if someone kept documents and left them on the blessed isles where Thresh later would discover them causing a chain reaction that would lead other void spawns to unlock their original formes and takeover the Darkin they intended to consume anyways.