Prince Aemon reached his twenty-sixth nameday in 81 AC, and had proved himself more than able in both war and peace. As the heir apparent to the Iron Throne, it was felt desirable that he take a greater role in the governance of the realm as a member of the king’s council. Accordingly, King Jaehaerys named the prince his justiciar and master of laws in place of Rodrik Arryn.
“I will leave the making of law to you, brother,” Prince Baelon declared, whilst drinking to Prince Aemon’s appointment. “I would sooner make sons.” And that was just what he did, for later that same year Princess Alyssa bore her Spring Prince a second son, who was given the name Daemon. His mother, irrepressible as ever, took the babe into the sky on Meleys within a fortnight of his birth, just as she had done with his brother, Viserys.
Fire and Blood, by George R.R. Martin, pg 309-310