She is giving him 10 years to think about his choice. 10 years is a short time in a demon's lifespan but it is more than generous to make a decision.
Aeternus nodded and said, "How generous of you. I doubt that I'll need that long to make the decision. There's really only one choice to make isn't there?"
The demon lord was beginning to like where this was going. Aeternus's attitude pleased her. He seemed to have accepted his fate.
Then he suddenly stopped. There was a group of cloaked demons running toward the center of the plane. They are probably returning from honest hard work. They are high-rank demons and also all have the same boost under a certain ability called the Oath of a Lord. So they are honest and related demons coming from a day of honest hard work.
"What are you doing?" The demon lord screeched again.
"Giving you my decision to your offer," Aeternus said as he stretched forth a hand towards the group.