Satan and the Son of God can be seen as foils in the poem: whereas Satan's envy of Adam and Eve leads him to seek their ruination, the Son of God (described as "the radiant image of [God's] glory") seeks to redeem them; the Son of God also replaces Satan as God's favored advisor and servant, which leads Satan to declare war against God and Heaven.
Yet Milton does not oppose Satan and the Son of God merely to make a point about good vs. evil—just as Satan often seems more fleshed-out and complex as a character than God, Satan also often seems more alluring and heroic as a character than the Son of God: the Son of God blindly follows God's orders (though he does defy God to offer mercy to Adam and Eve), affording no forgiveness to the other angels who follow Satan, although he believes Satan has duped them. Satan, meanwhile, boldly opposes God's absolute authority, without any guarantee of safety or redemption in the long run: he lacks the security that the Son (as God's only Son) enjoys. Milton underscores the fact that the Son of God chooses to walk in perfect harmony with God the Father, while Satan uses his will to defy God and assert himself.
