There is very little canonical information about Meleth. According to the Book of Lost Tales II she is a denizen of Gondolin and the nurse of Eärendil. She is noted for her vivid tale-telling, including stories about Morgoth 'at times of his (Eärendil's) waywardness'.
Meleth was born in Nevrast around the year 80 First Age, to one of the many mixed couples of Turgon's following. She was closer to her Noldorin father Nolemíre (Golmir), and one of her most cherished memories includes 'treasure'-hunting with him in the cliffs and beaches of Vinyamar after one of the frequent storms, as well as listening to his tales and stories of Valinor in its prime. Although she was heartbroken to have to trade the sea for the mountains, the idea of living in a likeness of Tirion excited her. However, that fascination was short-lived.
In Gondolin, the Sindarin part of her heritage soon came to trouble her; both Meleth and her mother Aelothiel suffered from sea-longing that could not be assuaged, and frequent conflicts in her parents' marriage including but not limited to the clash of diffferent customs (such as her father's insistence for Meleth to bear a Quenya father name, Mírelle, that she was forbidden from uttering by her mother due to Thingol's decree) drove Meleth to become self-sufficient early on. She entered into an apprenticeship with Pengolodh and became a loremistress primarily concerned with the culture and customs of Valinor, and Quendian beliefs, the latter a topic very close to her heart personally.
Quiet and shy already, Meleth withdrew further as her sea-longing continued to grow stronger, and could be seen sitting by fountains listening to the music of water for hours, staring at Turgon's fabled Belthil and Glingal by the palace, or retreating to a hideaway on the wall.
to be continued