When Aegon found out his father would remarry, he was less than thrilled about getting a stepmother. He thought his father would marry some old lady of the court so one could imagine his surprise when the news came out that he would be marrying a Dornish Princess, and her age is close to Aegons and not the old king she was set to marry.
This fact made Aegon suspicious. She surely must be deformed in some way to be married off to a king who was on the deaths door. Aegon held this ideal, silently smiling to himself when he and the rest of his family were waiting in front of the Red Keep watching her carriage come into view.
After a few agonizing minutes, the door opened, and she walked out. She was absolutely stunning. She walked up to Viserys, who kissed her hand, and then she moved down the line to Aegon. She was nearly a head taller than him, and he was starstruck.