Wide-ruling Agamemnon

My son asked me to entreat Zeus:
"Sit beside him and take his knees and remind him of these things
now, if perhaps he might be willing to help the Trojans,
and pin the Achaians back against the ships and the water,
dying, so that thus they may all have profit of their own king,
that Atreus' son wide-ruling Agamemnon may recognize
his madness, that he did no honour to the best of the Achaians."
Iliad 1.407-12 (Lattimore translation)

What hold does Thetis have over Zeus?