If they were mortal, Chaos might be amused by the irony in saying that they predate time. It was not until their daughter Gaia and grandson Uranus sired Cronus that it came to be, and to this day their relationship with their (great-)grandchild is cordial at best. Chaos lies at the outer edges of the world, and has little concern for the limitations their (great-)grandchild has placed upon it.

Still, they notice an interdimensional interloper drifting by the metaphorical window, and Chaos likes patterns as much as they like breaking them. So when Lord Hades's son will begin to attempt his little stunts at breaking the walls that confine him, that seems like the appropriate time for this visitor to arrive. All that the primordial Titan has to do is open the metaphorical window a little bit further, and here she is, touching the surface of their world, slipping through the membrane that keeps it from spilling outside.

When the young godling sees the portal and sacrifices a little bit of his vitality to go through, heedless of his own sanity and wellbeing, it is not Chaos who awaits him in these shadowy chambers.