Éowyn is an unusually complicated character in a series that tends to portray women as (a) beautiful, and (b) two-dimensional. Éowyn is gorgeous, of course (all the women in The Lord of the Rings are lovely), but she is also restless and unsatisfied with her life. As the niece of King Théoden and sister of Éomer, she sees the possibilities of honor on the battlefield around her all the time. But in this world, the fact that she's a woman means she can't join in the fray.
Éowyn doesn't only want glory. She also wants Aragorn. She sees his kingly nature and immediately swoons (as much as a steely woman such as herself can swoon). When Aragorn declares his plan to go to the Paths of the Dead, Éowyn actually gets on her knees to ask him either to not go, or else to take her with him. When he refuses both, Éowyn gets furious and frustrated.
Let's face it. Éowyn spends much of The Two Towers and The Return of the Ring desiring two things she isn't supposed to have: battlefield heroics and Aragorn. Éowyn solves her first problem—that she's not allowed to fight on the battlefield—by dressing as a dude and going with the Riders of Rohan to Gondor. She calls herself "Dernhelm," since "Dern" is an archaic word for secret or concealed. Her fake name means literally "helmet of secrecy."
We are a little surprised that no one guesses her true identity as she rides out. Rohan's not that big. Doesn't anyone wonder where this soldier who refuses to take off "his" helmet comes from? But it seems that she has some kind of deal with one of the captains of the Rohirrim, Elfhelm, who allows her to come along, perhaps with the knowledge of her actual identity.
Since Éowyn is an outsider who knows what it is to be rejected because of how she looks, she immediately sympathizes with Merry when Théoden insists that he return to Edoras to sit and wait while everyone else battles the Big Bad. So "Dernhelm" brings Merry along with her on this long ride to Gondor. But it's only on the battlefield that Merry fully understands why "Dernhelm" might feel pity for his situation.
When "Dernhelm" confronts the Lord of the Nazgûl who has just struck down her uncle, he mocks her: "No living man may hinder me!" (5.6.14). Éowyn whips off her helmet and declares, "But no living man am I!" (5.6.15). To which we say, you go girl.
This dialogue between the Nazgûl and Éowyn echoes a similar moment in the Shakespeare play Macbeth. We've already mentioned in The Two Towers learning guide that Tolkien was thinking of Shakespeare when he came up with the Ents (see our section on "The Moving Forest"). Macbeth also contains a scene in which the title character laughs at his foe, Macduff, because he has been told that no man "of woman born" (Act 5.vii.16) can hurt him. But Macduff was born by C-section, thus technically avoiding the "of woman born" label. So Macduff kills Macbeth.
Back in the world of The Lord of the Rings, long ago during the first War of the Ring, Glorfindel the Elf predicted, "Far off yet is [the Lord of the Nazgûl's doom, and not by the hand of man will he fall" (Appendix A.iv.43). So when the Lord of the Nazgûl stands in front Éowyn and thinks she's a man, he's totally sure he's in the clear. But when it turns out that Éowyn is a lady, that prophecy ("not by the hand of man") becomes a big problem. And of course, it is by Éowyn's hand that the Lord of the Nazgûl dies. Her gender, which she keeps thinking is a disadvantage because it keeps her out of battle, is actually the thing that allows her to rise up and do her greatest deed.
After the battle, when Éowyn has finally won the glory she has been seeking her whole life, she meets Faramir. You might think that Éowyn would be in a good emotional place right then, but no dice. The Black Breath has really done a number on her, and she is full of bitterness and despair. Plus, she's still recovering from her injuries in the Houses of Healing, so it's not the best time to start a new relationship.
Worst of all (from Faramir's perspective), Éowyn really wanted Aragorn. And she's not one to settle. But finally, Faramir's natural leadership abilities and lordly manner win her over: "something in her softened, as though a bitter frost were yielding to a first faint presage of spring" (6.5.23). This is the beginning of their love, and eventually, Faramir persuades Éowyn to marry him and go with him to Ithilien.
Frankly, we are a little creeped out by the gender relations implied by this whole relationship with Faramir. As long as Éowyn wants to be a kick-butt warrior lady, she is cold as "bitter frost." But then, she meets a man who makes her feel a bit foolish and inexperienced (Faramir's sternness makes her feel "like a child that has not the firmness of mind to go on with a dull task to the end" (6.5.17)). And it's Faramir's willingness to take charge that makes her feel like more of a real woman, and less of a shieldmaiden.
We think it's great that Tolkien includes a warrior woman in The Return of the King. But then, why does she have to give it all up in favor of marriage? Why does Éowyn have to choose between her career as a warrior and her family life with Faramir? These are unanswerable questions, but this relationship between Éowyn and Faramir really changes her character, in ways that make us think a lot about the gender politics of The Return of the King.