The argument becomes a bit more potent when you say “…if the intention is merely to flesh out the characters of Batman and Joker and the main premise of Joker’s ideology,” but that doesn’t work at all since that was hardly my point. You’re confusing the notion of fitting into a story with the notion of being subverted by the other characters. All of the characters have their places, and the story would be lesser for it if any of them were removed. In Nolan’s world, the Joker and his bizarre worldview are not complete without Dent, and Dent and his transformation are not complete without the Joker. Batman isn’t complete without either of these characters. When I made that point, I was trying to say that each character effects the other in a special way and changes throughout the course of the movie because of the actions of another character. Dent himself probably gets the most development in TDK (Batman was developed in Begins, and the Joker is more about his ideology). In fact, Nolan called Dent’s story the backbone of the film, so he hardly underplays it.

My entire point in saying that Dent was fulfilled thematically was to say that he was fulfilled as a character, and I thought that came with an assumption. He went on a suicidal rampage. That was it. He was not coming back from that. Rachel’s death had destroyed him, and he wanted revenge. That in itself is development and the final arc of Dent as a character. Nolan doesn’t use Two Face as half of one character where one half has to be given this much development and this half has to be given this much development. He uses Two Face as an outward scar upon Dent’s fall. And like a lot of films, the fall deserves much more time than the final act – and Two Face is a final act. It’s sort of like Taxi Driver in that regard. The final act of destruction occupies only a small percentage of the movie. The real meat is seeing the character get there. In other words, the setup is the fall, and the final destruction is saved for when all of the pieces are moved into place. That was the point I was trying to get at, and you haven’t really addressed why that is not good enough. In repeating the same tired rhetoric about characters dying off upon their transformation, you have yet to establish why that in itself is bad. You have yet to establish why the character’s arc isn’t fulfilled. You keep making claims, but you don’t offer any reasons.

The Joker argument is a hard one to make because of two reasons 1) he’s a theoretical criminal and 2) they don’t show his “organization”, and thus we don’t have a head count (the amount he kills might not be significant) and we don’t know how exactly he rewards some criminals. Outside of the first scene he barely kills anyone without a very good reason and not any more than the typical criminal trying to inspire fear that’s standard in these types of movies, but the bank scene is sort of problematic. He obviously killed them for a reason – he never intended to share the money – and it’s a one time situation where he needed to do it, but it demonstrates a resolution to kill who he doesn’t need. And that leads to number one. Men who kill for pleasure usually do so in small doses. They want to savor it. Men who kill on a large scale usually do so for a cause or because they want something. They just want people out of the way. The Joker is a mixture of the two. Because he doesn’t value anything, there is nothing to destroy him with. That’s why the mob needed him in the first place. The mob valued something. Batman used that to squeeze them. So they used the Joker. Only the Joker walked all over them. If Joker is the only game in town, then where else do they turn? Perhaps he would have been done in eventually, but he was on a near suicidal mission anyway. In fact, the man played by his ideologies. If he was willing to let Dent shoot him in the head, then he’s admitting that chaos doesn’t favor any man. He lives by those rules, so he’s willing to die by those rules. However, he protected himself from that rather well since he knew exactly how to inspire loyalty in the moment. He tempted men with billions of dollars. One of the mob guys in the beginning is slowly being squeezed by Batman. He barely escapes capture, then later he follows the Joker. He’s walking right to his death just because he thinks he’s getting his share, which by using that same character was probably intentional of Nolan. In fact, that’s the entire point of the line, “And then we’ll see how loyal a hungry dog really is,” because he says it in the context of the goons’ loyalties. Nolan is trying to make the point that in their desperation these small and middling criminals will run to where the money is, even if they get their heads chopped off in the process. As the Joker slowly takes out their leaders, they will turn to him so that things will get done. And as long as he has the power to get things done, he has the power to control them.

“And you have yet to say why that can’t be. Sure you’re saying it. You’re saying, “because this is the way it is.””
Wrong. Here’s what I said:
Don’t. Use. Dent. For that part if the intention is merely to flesh out the characters of Batman and Joker and the main premise of Joker’s ideology.
And:
Because Dent is the beginning of Two-Face, just as Bruce Wayne is the beginning of Batman. Bruce Wayne would have failed as a character if he died the first time he swung from the rooftops as Batman, or the first time he tried to fight a gang of thugs.

As far as Nolan’s intentions, he should not give Dent a new name — Two-Face — regardless of whether or not it’s fulfilling his purpose. It’s not about Dent, or Two-Face, it’s about Nolan seemingly creating this brand new character at the end, and then killing him off before he actually becomes that character. Maybe it fulfills Nolan’s story, but it does so at the cost of the character he’s spent the movie developing, regardless of who or what that character is. As Aristotle stressed, narrative is about story AND character. The aim is not to stress one over the other; the goal is to make them BOTH work for the narrative. Nolan did not do that with Dent. Is that something you can comprehend?

“What’s the point of arguing if you’re not going to use the full extent of logic?”
What’s the point of writing if you’re not going to use the full extent of literacy? I.e.–what the hell does that question mean?? Getting a bit above your head there… I have addressed each and every one of your criticisms and arguments by specifically quoting and then answering them, though you’ve not done the same with me. Do not talk to me about the orthodoxy of arguing when you yourself play loose and fast.

“Honest question: does the movie ever state that he killed all of his thugs?”
Honest answer: of course not. What a ridiculous question. He does, however, kill all of those thugs working for him in the beginning of the film, and kill another crime boss he’s working with at the end, and then kill several in the middle. This is sufficient evidence for my claim that he is not a stable or trustworthy employer to work for — even for a criminal’s standards.

I get your argument. But you haven’t made a case. You keep going on about what Dent should be and have yet to answer why, repeating the point about characters getting killed off early. You ask why not, and I say…why not? Whatever suits the characters thematically through Nolan’s brilliant vision. As long as it makes complete sense in the story because according to Nolan’s story, this is who Dent is and this is how Two Face goes on a suicidal mission. Your question presupposes that the characters aren’t well established when they are killed, but Dent’s transformation into Two Face is explicit. The onus isn’t on me because that’s my answer. Dent fits into the story thematically the way Nolan wanted.That’s been my entire point all along, and I’ve made it pretty clear. Dent may be the beginning of Two Face, but Two Face is the end of Dent. They are one complete entity, one complete story. Nolan is treating them as one complete story, and so I say aloud…why not?

And you have yet to say why that can’t be. Sure you’re saying it. You’re saying, “because this is the way it is.” But that’s not an argument. An argument makes the other side see your point. I assume that you come from the traditional mentality of this is the way he is and that’s how he should be. I don’t come from that position, so even if I don’t like it, you have to make me appreciate it. You have to make me respect your reasoning. You’re not even cultivating your entire position and making yourself clear. What’s the point of arguing if you’re not going to use the full extent of logic?

Honest question: does the movie ever state that he killed all of his thugs?

Either way he is dead.

I agree (and have always thought) the way Two Face died was stupid… but how on earth was it ever “debatable”? The movie showed he was dead, they said he was dead and they had a funeral. I still don’t get why anyone thought this was a mystery.