Under Gwen's rule, Camelot flourished. Magic returned to the kingdom, and it was not very often that they had to deal with sorcerers gone mad with power. Nobody ever dared attack a Kingdom where a sorcerer as admired as Merlin lived.
Gwen never remarried, and as such never had any children. It was something she'd always wanted, especially having seen all her other friends get married and become mothers themselves. She'd always loved being around children, and was known by quite a few of the knights young sons and daughters as Aunty Gwen; a role which she'd adopted happily.
There was one child she'd always been most fond of. He was Leon's eldest son, named after her brother Elyain, and as he grew up, developed all the virtues that a knight should.
When Gwen grew quite old and knew her death was nearing, she made the decision to name a new ruler. Most had expected her to choose Merlin; a good friend and advisor. After all, what could be better than a king who would live forever? But Gwen knew that Merlin was no king. He was a gentle soul, better suited to guiding then leading.
So she chose Elyain; who had grown up to be the most loyal of men, just like his father. Gwen knew that a Pendragon would never again hold the throne. People had suggested to her many times over the years to simply fix that problem with magic, but she was sure she had made the right choice. Magic had no place in the roles of birth and death. Merlin assured her that Arthur would have felt the same way.
Gwen died happy in the knowledge that Camelot was in good hands.