An Empty Eye Socket Equals a Facial Scar?
Why Lyle did not rescue Thea from Lensol Castle...
Let us review what was said by the soldier in Lensol Castle:
A long time ago, a dragon grabbed a woman out of the castle dungeon and flew away. But I managed to leave a scar on its face!
We know that the person who rescued Thea had the ability to transform into a dragon. That fact leads most people to believe that Thea's rescuer was her father Lyle, as Lyle is the only character in Phantasy Star III who is shown changing into a dragon and back.
I, however, do not believe that Lyle was responsible for Thea's rescue. It cannot be ignored that Lyle was in particularly bad health at the time of Thea's abduction. In the worlds of both Ayn and Nial, Lyle lost his eye prior to the attack on Shusoran. (We know that his eye was lost in Nial's world as well as Ayn's world because, during the quest of Nial's son, an old man in Agoe town says that he knew a one-eyed knight named Lyle.)
After the survivors of Cille and Shusoran have taken shelter in a cave in Aridia, a yellow-robed noble tells Ayn that Lyle is in poor health and may not live long. There is no reason to believe that this would have played out different had Ayn not been born. (Ayn was nowhere near Cille and Shusoran when the attack took place, and therefore is not a factor in how the battle unfolds. Also, note that the battle at Cille and Shusoran is apparently yet another event that occurs no matter what character is played.)
In Ayn's world, Lyle was unable to go to Thea's rescue himself. Why should we believe that in Nial's world he was any more able, especially when we know that his health was terrible?
Also, at the end of Ayn's quest, Lyle assumes his dragon form so that he can carry Ayn and his companions across the sea to where their final opponent waits. Lyle died as soon as he changed back to his Palman form, so it would appear that the exertion of transforming into a dragon and back, as well as being very active while in dragon form, was what finally killed him. Therefore, it does not make sense to believe that Lyle, in such a poor condition, could make his way from Aridia to Draconia, assume dragon form, break through the sealed gates of Lensol Castle, fight all the way into the dungeon, open Thea's cell, carry her back out of the dungeon, and then escape the kingdom before exhaustion overtook him. It is because of this that I believe that a different Dragon Knight must have been responsible for Thea's rescue.
Lastly, it has been said that the fact that the dragon's face was scarred and Lyle's face was damaged proves that the two were the same. However, Lyle was never shown to have an actual scar on his face -- he had simply lost his right eye. Even more importantly, Lyle's eye was lost some time before Thea was ever kidnapped.