In the Milky Way dimension.
Thanos soon noticed Quicksilver fighting Sals.
He gave a faint smile and paid it no further attention.
At his level of power, he had more or less figured out what the Four Great Deities were fighting over.
Souls.
Recently, he had conducted a thorough study of the Milky Way's Black Hole, one of his true bodies.
He had discovered that Origin Power and souls had something in common: both were made of Fundamental Particles.
These Fundamental Particles interacted in a peculiar way. They could communicate and influence one another without clustering together to form Quark Particles.
But his power had only reached Universal Level, and he could observe matter only down to the quark level. He could not examine Fundamental Particles in detail.
He could only piece together a theory from uncertain observations and speculation.
After all, the Mind Source Stone could absorb the Mental Energy of living beings and convert it into Origin Power, while the Reality Source Stone could not absorb matter and convert it into Origin Power.
The difference was souls.
And if souls were what the Four Great Deities were fighting over, everything made sense.
Why did the Four Great Deities keep scheming, yet never intervene personally even when they lost or were outwitted by the universe's inhabitants? Why did they even protect the universe?
Why was his Origin Power stronger than that of the other Dimension Lords? Because it came from absorbed Mental Energy, not from the Black Hole.
And why did the birth of a Celestial require the destruction of a planet?
Because it needed to absorb enough souls at the moment of its birth.
Intelligent Life was nourishment for a newborn Celestial.
That also explained why Tiamut in his dimension could delay his birth without destroying Blue Star.