Myrrh(ミルラ Mirura)is the "Great Dragon" from the Darkling Woods in Caer Pelyn. She is the adopted daughter of Morva, the Great Dragon who helped mankind in the first war against the Demon King.
During the course of the game, she disguises herself as a girl to find the great evil that plagues the lands, yet is captured, stripped of her Dragonstone, and is about to be sold, but is saved by Ephraim. Afterwards, she accompanies Ephraim for much of the game, and is guarded by Saleh.
In battle, Myrrh uses her Dragonstone to transform into her dragon form; once said Stone is exhausted, she can no longer transform.
Myrrh is arguably the most humble, lonely character in The Sacred Stones. Most everything that she says is in concern for the person she is speaking to, and she rarely ever speaks otherwise.
Although she seems to prefer the solitude she so greatly exudes, Myrrh actually longs to have close companions around her. For example, in her support conversation with Ephraim, she asks him if she could call him 'Brother'.