Unfortunately, she dies before he has a chance to speak with her. With her death, he suddenly realizes he has no reason to stay in Atlantis, and beats up his guards and leaves. Later, after Arthur has gone out into the world and become a superhero, he returns to a freed Atlantis (the other prisoners were inspired by his example) and finds out that his Mother was actually the former Queen. When the King and Vulko urge him to take the throne, he refuses, pointing out that he was left to die by his mother. Vulko explains that it wasn't the case at all. She didn't even know.
With that knowledge, he decides to become King.
Happy Mother's Day to all...