Gravis left the Eternal Fire Sect without any fear.
He had known from the very beginning that he could do what he wanted.
Gravis knew the True Law of Control and the True Law of Freedom, which meant that he knew more about these two things than any Peak Divine God in existence.
He knew exactly how much control he had, and he also knew exactly how much control the other side had.
In a fight, the Sect Master of the Eternal Fire Sect could sneeze Gravis out of existence, but Gravis was still the one in control.
As long as she couldn't stop Gravis from escaping, he would be the one in control.
If she had decided to attack, Gravis would have simply activated his Law of Perceived Reality. Sure, the Sect Master would be able to see through it if she questioned her own perception, but she wouldn't do that.
In her perception, she would have killed Gravis.
Then, she would have left.
Gravis wouldn't even need to move.