Milton's Satan is one of the most dynamic and complicated characters in all of literature. While he possesses an unhealthy thirst for vengeance and havoc like the little red dude with a pitchfork you're used to seeing, Satan is also the most likeable character in the poem. OK, maybe likeable is going a bit too far, but nearly every reader of the poem has found it difficult to avoid sympathizing with him to some degree, if not completely. For many years readers of the poem have been divided over the question of whose side Milton was on: Satan's or God's.
Just bear with us here. Satan is flat-out, hands down, without a doubt, the best speaker in the poem. He's like the greatest Shakespearean actor you've ever seen. When he wakes up in Hell, chained to a burning lake, how can we not feel a bit sorry for him? All he really tried to do was overthrow God, which is impossible anyway because we're talking about God here. Yeah we get that he's God, but when we actually meet God in Book 3, he doesn't even compare to Satan. He comes off like some boring unnamed character, whereas Satan is like an evil Hamlet, or Iago, or any other major character that isn't a talking corpse (check out his famous speech on Mt. Niphates in 4.32 to get a sense of Satan's Shakespearean flavor). The great English poet Percy Shelley, who idolized Milton, summarized the point well:
Nothing can exceed the energy and magnificence of the character of Satan. It is a mistake to suppose that he could ever have been intended for the popular personification of evil.
Sadly, however, Satan really is evil. But his is a very seductive kind of evil, which makes him even more dangerous (just think Tom Riddle from the Harry Potter series). Let's consider an example. We just said that God seems like a boring, authoritative figure; well, that's how he comes across. But that's also what Satan would love for us to believe about God. In Books 2 and 5 especially, Satan does a great job of portraying God as some type of fascist despot or tyrant who loves arbitrary power. Sometimes, Satan even acts like he's some kind of innocent victim.
OK, God's power is arbitrary, that much is true; but he's also the boss. It's his universe; he created it. All he wants from Satan, and everybody else, is a thank you in the morning for being allowed to live in Heaven….FOREVER! Is that really so much to ask? Does that sound like despotism? Not really. But listening to Satan's impassioned speeches and their infectious rhetoric might make you think so.
It turns out, conveniently and ingeniously, that Satan's speeches are uncannily like the animal whose shape he dons to tempt Eve: the serpent. They are tricky, clever, wily, and anything but straightforward. For example, whereas Satan will champion some type of heroic perseverance or a refusal to repent and submit to God's slavery, he's really just ticked off that he lost the war in Heaven and that he has to live in Hell. He knows that his auditors (which include us) love that kind of rhetoric, which has proven successful and seductive for centuries.
Sometimes, Satan tries a different angle; at one point he even sheds a tear, a moment that bears some similarities with the sadness he feels when he sees Adam and Eve in Paradise and realizes he's screwed (he actually says "Oh Hell" at that moment). Poor Satan, right? Wrong. He really just wants to make Adam and Eve suffer to spite God; he wants to ruin it for two human creatures who, from one perspective, are his brother and sister (they're God's creations too). Adam and Eve had nothing to do with his spat with God; they're just pawns in Satan's game, innocent victims whom Satan cruelly takes advantage of.
OK, we get it: Satan is a great speaker, but he's a really mean dude. He's smart and knows what everybody wants to hear, but he's also very dangerous. Why then, does he take up so much space in the poem? Why is he without a doubt the most interesting character in Paradise Lost? Before we meet God, the Son, Adam and Eve, or anybody else, we meet Satan. In fact, his is almost the only voice we hear for the first two books of the poem! We can see why he's attractive, but our buddy John Milton's motives for letting the villain steal the show are more complicated, especially considering the poem's supposed purpose of "justifying the ways of God to man."
The question of why Satan gets so much face time is difficult to answer; one reason that Satan is so attractive and dominates the early books of the poem is because Milton wants us to be seduced, wants us to be lured by Satan's infectious words only so he (Milton) can correct us later and show us the error of our ways. In this way, Milton re-enacts the Fall for his readers: like Eve, we buy into Satan's arguments, only to suffer the punishment of Milton's rebuke. Similarly, when we first see the Garden of Eden it is through Satan's eyes. When Satan sees what he's excluded from, it suddenly becomes clear to us what the consequences of siding with Satan are: we won't be able to get into paradise (exactly what happens to Adam and Eve in the end).
But one could easily say that Milton doesn't want us to succumb to Satan's snares. In that case, Satan becomes another temptation to resist. Throughout his writings, Milton champions a notion of trial, whereby virtue is meaningless unless it confronts and resists temptations, dangers, etc. From this perspective, Milton is testing us as readers, attempting to appeal to the good angel on our shoulder over the attractive but ultimately evil devil on the other shoulder.