(It's possible I'm missing information from outside the 5 series books)
Here's everything we know about Lewyn:
-He was the younger brother of the Princess of Dorne (Prince Doran's mother).
-He served in the kingsguard to Aerys the Mad.
-King Aerys used his niece, Princess Elia Martell, as a hostage to ensure his loyalty (called into question perhaps by whisperings from Varys about Rhaegar's supposed plot to seize the throne).
-He fought and died at the Trident (283 AL) during Robert's Rebellion, mortally wounded before being killed by Ser Lyn Corbray.
-Jon Arryn returned his bones to Sunspear while putting down any notion of a second Dornish rebellion.
-According to both Arianne and Ser Barristan, he kept a paramour.
-Arianne says his paramour was a "rare beauty in her youth."
-Arianne implies that his paramour is still alive (possibly indicating that Arianne knows who she is).
-Ser Barristan says that Lewyn shared this knowledge with him, but it is clearly not widely known as Ser Arys Oakheart is somewhat shocked.
“Yes,” she said, “that fine white cloak. You forget, my great-uncle wore the same cloak. He died when I was little, yet I still remember him. He was as tall as a tower and used to tickle me until I could not breathe for laughing.”
“I never had the honor to know Prince Lewyn,” Ser Arys said, “but all agree that he was a great knight.”
“A great knight with a paramour. She is an old woman now, but she was a rare beauty in her youth, men say.”
Prince Lewyn? That tale Ser Arys had not heard. It shocked him. Terrence Toyne’s treason and the deceits of Lucamore the Lusty were recorded in the White Book, but there was no hint of a woman on Prince Lewyn’s page.
“… paramour,” Ser Barristan finished, before the Dornish knight could say anything that might besmirch the queen’s honor. “That is what you call them down in Dorne, is it not?” He did not wait for a reply. “Prince Lewyn was my Sworn Brother. In those days there were few secrets amongst the Kingsguard. I know he kept a paramour. He did not feel there was any shame in that.”
-We do not know his age, but his nephew Prince Doran is currently about 52 (b. 248 AL) and would've been 35 during the Battle of the Trident, so it likely Lewyn is somewhere between 35 and 55 at his death (somewhere in the middle or older, I'd imagine).
-It is never explicitly stated, there is a decent chance that he was at the Tourney of Harrenhal as King Aerys, Prince Rhaegar, and Princess Elia Martell were there (I don't believe it's stated whether Queen Rhaella or Viserys were there or if they had KG guarding them wherever they were).
Edited by Full-Faced Braavosi, 20 January 2013 - 08:46 PM.