Myrwin paused to consider that. William seemed honestly sincere, but Myrwin hadn't rised as far as he had by being a complete fool.
"Your sister's life stands as guarantee to mine and my own." he said after a few long moments. "If any harm should happen to become any of my family, she dies. Publically and slowly." he said. "That, and ten thousand crowns donated in Princess Elia's name to the nameless and poor of the kingdom will suffice." he said simply.
"Plus, Princess Genna and my retinue will be returning to Dorne inside of a month. I may or may not leave Elia here to act as my ambassador, or send someone more ... expendible." he mused.