Estraea was bubbly and would liven up the space. At first, he had a hard time matching her dynamics, but he then later learned how to control and manage his ways safely.
The Absolute lived with Estraea for thousands of years, just enjoying the universe to themselves and interacting with each other. Sometimes, they would create new inventions that would then be applied to the universe.
Just like the Absolute, Estraea had the power to create because she was bestowed with the Creation Magic as her core.
She was the sole wielder of the magic because it was very imbalanced and would impact the universe severely if held by multiple people. It would stay that way even after many years passed. He couldn't think of another person or being that would be more suitable in taking care of the power other than Estraea.
Either way, it would be a great way to separate her identity from the others. She was his special companion.