|Born||At the Reach|
|Book(s)||The World of Ice & Fire (mentioned)|
Ser Mervyn was standing guard at the door to Queen Jaehaera Targaryen's chambers on the occurrence of her death. Mervyn killed his own sworn brother, Ser Marston Waters, during the turmoil of the regency after Marston tried to have Mervyn arrested.
Behind the Scenes
- The World of Ice & Fire, The Targaryen Kings: Aegon III.