Two nations warring in the womb. The clearest picture of this hostile-brothers pattern is Christ and Satan, the closest thing scripture offers to a pure archetype of the two eternal responses to being. One brother greets the given world with gratitude and works to redeem it; the other meets the same world with resentment and moves to corrupt it. That antagonism does not begin at some later moral crossroads. Already, before either child draws breath, the two are coiled in the same body, born of the same mother.
Then the prophecy overturns the natural order: the elder shall serve the younger. Rank by birth, rank by strength, rank by every visible measure gets inverted. What deserves to lead is not the firstborn or the stronger but the right orientation of the spirit, and that cannot be read off the surface of a man.