The primacy of mothers in fashioning heroes and their lifelong involvement
in maternal vengeance and vindication are acknowledged in the Iliad,
but in sanitized ways. Agamemnon grudgingly links Achilles’ preeminence
in might, divine birth, and special favor among the gods: although Achilles
is very strong and his mother is a goddess, to Agamemnon he is “the most
hateful of all the kings whom the gods love” (1.176–78). Thetis’s recollection
of “the best of childrearing” emphasizes the importance of careful nurture, in
addition to divine parentage.

I gave birth to a son who was without fault and powerful
[amumona te krateron te],
conspicuous among heroes; and he shot up like a young tree,
and I nurtured [threpsasa] him, like a tree grown in the pride
of the orchard (18.55–57)

Goddesses like Thetis and Demeter, who enlist sons in their service and
reward them with honor, glory, or immortality, earn a special epithet: kourotrophos
(nurturer of youths).

The epithet is apt because of the central role that their kind of mothering
plays in heroic culture. They rear kouroi, youthful hero-sons with short life
expectancies. It misleads only in suggesting that the nurture is benign, a superior
variant of ordinary mothering. Mother-son interactions in the Iliad and myth
suggest that the actual mother-son relationships reflected in them are forms of
role-reversal. Mothers sacrifice sons’ needs for nurture, and their development
into secure and confident adults, to assuage insecurities about their own worth
and to validate maternal claims to superiority. Kourotrophos mothers couple
traumatic rejection with a requirement that sons respond to it as if it were loving
nurture. Such is the nurture that produces perfect hero-sons, or kouroi.

Becoming Achilles, 108-109