This Sidhe is pale green-skinned and green-eyed, her dripping hair entangled with seaweed, and looks about eleven or twelve years old. She first called to Lucas as the heroes approached Avalon during the adventure of The Bonita's Treasure in Julius 1668, and appeared to him when he reached Carleon. She told him then that she wanted him to kill "their mother."
She appeared again when the heroes sailed from Freiburg to La Reina del Mar in Primus 1669. This time, she approached on a Sidhe vessel made entirely of water, and showed herself to all the heroes. She told Lucas that he would have to kill her mother before another year had passed. Questioned, she stated that her mother was Queen Elaine... Then she demanded that "the one who had received the prophecy", Constanza, be handed to her immediately. When Lucas refused, the Sea Lady departed but her troops of undead sailors attacked the Maris Stella.
Then she greeted them when they ran into Bryn Bresail, trying again to get Lucas and Constanza to come to her. She threatened to sink them, but stopped short.
When the heroes had to sail around Avalon again in Tertius 1669, she revealed that the man who had thought of himself as Lucas for the past year was in fact a changelling, and that the real Lucas had been her prisoner for a year under the waves, since falling to the Sidhe Reavers. Lucas the Changelling agreed to her terms and promised to make an attempt on Queen Elaine's life at some point in the future, and the real Lucas was released.
In Septimus 1669, the Changeling's attack appeared imminent and Lucas hurried to Avalon with his companions, to stop the murder attempt. Meryth sank the Maris Stella but the heroes managed to reach Avalon nonetheless. They were too late when they tried to reach Queen Elaine before Meryth did. Then the truth came out: Meryth is not actually Sidhe; she is Elaine's daughter, bent on destroying her mother. She has been raised as a weapon by the Queen of the Sea. Meryth disappeared, and the heroes have not heard of Meryth in the five years since these events.
