Thetis

"Eyes with with tears,
he spoke, and her ladyship his mother heard him
in green deeps where she lolled near her old father.
Gliding she rose and broke like mist from the inshore
grey sea face, to sit down softly before him,
her son in tears; and fondling him she said:

'Child, why do you weep? What grief is this?
Out with it, tell me, both of us should know.'"

(from Homer's The Iliad, translated by Robert Fitzgerald)

Her father was Nereus, considered an ancient sea god, son of Pontos and Gaea, who obtained a position under Poseidon and had the power of prophecy. Doris and Nereus had offspring of fifty, or perhaps one hundred, daughters, called the Nereides or Dorides, of whom Thetis was one of the most famous, at one time desired in betrothal by Zeus. Zeus was warned by Themis that such a union would produce a son who would surpass Zeus in might, so he withdrew from his engagment and Thetis the sea-goddess was given in marriage to Peleus, a young and pious prince of Phthia, in Thessaly. Together they bore the son, Achilles.

"Thetis
had kept in mind her mission for her son,
and rising like a dawn mist from the sea
into a cloud she soared aloft in heaven
to high Olympos. Zeus with massive brows
she found apart, on the chief crest enthroned,
and slipping down before him, her left hand
placed on his knees and her right hand held up
to cup his chin, she made her pleas to him:

'O father Zeus, if ever amid immortals
by word or deed I served you, grant my wish
and see to my son's honor! Doom for him
of all men came on quickest. . .'"

(from The Iliad, as above)