What is it about Batman that fascinates us so much? Why do we root for the tormented soul? What does he allow us to do that other superheroes (or the majority of other heroes) don't? Why won't he die? 
 Reading Miller's take on the Dark Knight is a fascinating study in your own expectations and how, as a reader, the myth of the subject can overwhelm what is really there. It is also fascinating because, despite Miller's best efforts, I rooted for the caped crusader again. I want him to live forever. But Frank Miller doesn't. 
 At least, not as Batman was. 
 Because this book is a deconstruction of Batman. 
 Whereas Watchmen is a celebration of the Golden Age of Comics, with a brief touch on the idea that superheroes can make the choices that regular heroes cannot, The Dark Knight Returns is a pointed barb that demands we - as readers - take responsibility for the power we've given these vigilantes. Miller, along with the illustrative and coloring powers of Klaus Janson and Lynn Varley, has created a Batman who is no better than the villains. Unlike the film adaptations (almost all of which have been influenced by this book in many obvious ways), Batman is not just there as the gel to talk about cool villains; instead, Batman is the focus of this story and suffers from his own psychosis. After all, we are looking at a man who wanted more than revenge. Here was someone who used his parent's murder to cover up his own inner demons; his own sense of justice. This inner drive is what forces the old Batman to get up and take the mantle again. 
 That is, Batman is insane. The difference between his insanity and that of the Joker is that Joker is dedicated to chaos (as is Two-Face, whereas the Mutants are about claiming things for their own, more on them later), and Batman is dedicated to structure. Batman sees the world as a horrible patchwork piece that needs restitching. Bruce Wayne (who, appropriately, only appears in the first of the four parts) needs to destroy the darkness around him to destroy the darkness within him ... but the darkness within him IS him. And that's Miller's thesis: there is no Bruce Wayne, only Batman. Whether there ever was a Bruce Wayne can be debated, but that what exists now is solely Batman cannot be debated. The series opens up with Wayne/Batman locked in his mansion the way Joker, Two-Face and others are locked in Arkham Asylum. Victims of their own madness and forced to play out their game one more time. 
 So an insane 55 year old man has had enough of watching Gotham deteriorate into a giant crime-ridden mess (like that seen at the start of Batman Begins) that is run by a gang known as The Mutants. He ventures out, unable to fight the Batman inside of him (because that Batman IS him, to defeat Batman is to die), and starts to dole out his brand of justice to the city around him. But ten years has passed and society no longer wants a dark vigilante who leaves the "bad guys" with broken bones and laid up in hospitals. Not dead - Batman refuses to kill - but close enough that they won't do whatever bad thing they were doing before. 
 The Mutants play an interesting role in this book, not just as the instigator, but also as the constant malleable enemy that Batman would fight when the other major villains were on vacation. The mutants split up when their boss is destroyed. Those who watched Batman defeat their boss take on the mantle of the caped crusader and call themselves Sons of Batman (S.O.B.'s ... yes), while others dress up as Nixon or Nazis (with the swastika tattooed on various parts of their body) or whoever will hire them. They become, in essence, the goons for hire that work for our big villains in the movies waiting for their moment. As if there is a criminal element there that lies waiting for Gotham and always is there waiting. In the end, the people themselves take on the role of Mutants - both SOB's and evil - in the riots but claim they didn't know what they were doing. So is Batman wrong to desire this level of justice all the time? 
 The myth of Dark Knight Returns is that it's dark and violent. Well, this myth is much like the myth of the Batman; the criminal element (the readers) must always expect it to be worse than it really is for the man (book) to work. Was it a slap to the face back when first released ... I can only imagine. This was a time when most knew Batman through Adam West, and here Frank Miller ran that image through the ringer to emphasize the psychological pain Batman had and instilled in those around him. But this was not to glorify Batman - or to make it dark/gritty/whatever - but simply to state that such a man could not actually exist in the real world without there being an effect spread to all people around him. The Batman of the 1960's is closer to Superman. The Batman of Dark Knight Returns is a washed up ex-superhero with a vendetta against crime that won't let him stop. Is there violence then? You bet! But is it to the degree that I expected ... no. I heard that there was rape in this book and lots of blood ... well, yes and no. The most offensive things occur off-panel; and the absolute worst is only mentioned after the fact. Batman is the one who bleeds the most in the whole book, and that blood makes an impact because it is used so sparingly. This is violence used to keep us from rooting for violence, and to look at blood and fighting and guns in that way is significantly darker than the fairy tale that most James Bond movies show. 
 So the darkness was due to a paradigm shift, not a tonal shift. The violence was also a part of the story and the paradigm. And this is not entirely clear in the movies that have used Miller's work as inspiration. 
 Batman (1989): Maybe the most successful unison between Adam West and Frank Miller ... this is a Gotham that is crime-ridden and someone must change it. This is a Gotham where the crime is urban and small scale, crime that occurs at night to make the people fear crime. Batman plays on this fear, but there is still a lightness. Why? Because the focus is on Joker, not Batman. 
 Batman Returns, Batman Forever, Batman and Robin: From one of the greatest Batman films spawned this list of movies (that are unevenly successful). What happened? Well, they kept dark sets but put in Adam West as the crusader. Again, the focus is not on Bruce Wayne/Batman. In fact, all three of these have at least 2 villains to examine ... which missed the point of Miller's vision. The villains are a reflection of Batman (as Batman says while staring at Two-Face's whole face in part 1 of the comic), but this is only clear if we focus on Batman and keep the villains as side stories. 
 Batman Begins, The Dark Knight, The Dark Knight Rises: Christopher Nolan tried, he really did. He pulled out many plot points, had a tight story (for the first two anyway) that made the villains an effect of Batman (a theme discussed in Miller's book), rather than the focus of the Batman movies. The aim for realism was also meant in good faith ... but we have a hero to look up to and root still. And here's where darkness for darkness sake doesn't work - Miller was destroying a myth and investigating the worst elements of that hero ... Nolan praises Batman for the work he can do and then gives Wayne a clean slate (ha! like the program!) to live the rest of his life healthy, wealthy and wise. Demons defeated, life is good. Which doesn't deconstruct the mythos of Batman ... it only rebuilds it in a darker town. 
 TL;DR - This is a great book that destroys Batman by examining his flaws. This is not about creating a dark world where tortured souls can come out on top ... this is about creating tortured souls who turn their world dark and wondering why we idolized them in the first place. A classic for good reasons ... though a little too pessimistic for a reread.