By TDKR, Joker doesn't exist anymore. It's like they erased him from history. It's a shame too because I'd argue that the Joker in Dark Knight alone (as a single entity) is better than TDKR as a whole!
For the hypothetical folks that live under a rock that didn't see Dark Knight but did see TDKR, you could easily say that the mob offed Rachel and drove Dent into madness with the way it's handled in TDKR. Lack of Joker anything was deliberate.
I'm with most people that think it was lame that the character didn't even get one mention in the entire movie/story. A movie that heavily delves into anniversaries, holidays, "that night, this night exactly 8 years ago" and mentions/includes almost
every secondary character (i.e. the non-Alfred/Fox/Gordon gang)from previous films. Bruce's parents, Rachel, Dent, Gordon's family, Mayor Garcia, Crane, Ducard/Ra's Al Ghul, freakin' Fredricks!?! Hell, we even get to see the Batbunker and pretty much everything Bats had used at that point (I saw the Hong Kong cape backpack, the Begins gauntlets, the pneumatic mangler, etc.)
Let's face it, as far as the city goes, the Joker was just as damaging and influential as Batman and Dent, if not moreso. Yet 8 years later, everyone seems to have the latter two on their mind, but not the Joker. Doesn't make sense. Sure, you could say "oh, who cares he was a bad guy, a terrorist that people purposely put out of their mind when he disappeared". But couldn't you make the same case about that "thug", Batman? I mean, how can you bring up the SWAT team take down, Harvey Dent and Rachel every few scenes (and in some cases, with flashbacks), but you can't give ONE nod to the catalyst of pretty much all of that? Ridiculous. We know why they didn't and this has been discussed to death, but from a story standpoint, it is jarring.
- Lame ass "Harvey Dent Day"? Thank the Joker.
- Two-Face in general? Thank the Joker.
- Bruce Wayne moping and feeling like he can never love/live again because of Rachel? Thank the Joker.
- That little, "clever", SWAT take down at the Prewitt building? Because of the Joker.
- Lack of mob or "organized crime" and the Dent act. Thank the Joker.
I'm sure there wasn't a soul in the theater that didn't have the clown prince of crime on their minds during their viewings of TDKR. How could you not? He's mentioned, referenced and established in Batman Begins, he's an integral key player in The Dark Knight. In TDKR? Absolutely nothing. We're really meant to believe that the Joker just laid low after all the stuff he pulled, either dead or kept hidden away in some deep, dark dungeon? No way. He was practically three steps ahead of everyone, including Batman. Look at his MCU shenanigans
while he was behind bars. We're really meant to think that the SWAT team successfully scooped him up for the state to deal with? What did he think of the cover up. Imagine his reaction to hearing that Batman took the blame for Dent's crimes. What was his court hearing like? Insanity plea? He's really going to let Batman go into self imposed exile without one more scheme to stab at Gotham's soul? As far as stories go and the Trilogies fictional "history", it's asinine to think a character like this just gets whisked away, never to be seen from again. Especially when we've seen him in these situations before,
There's just too many questions. Lame that we don't get that, but we get inserted stories about Italy vacations, Orphanage visits with supermodels, feelings in your bones, and super exciting clean energy nuclear bomb projects.
Still, I'm kind of glad the Joker wasn't included in any way, shape or form. He's one of the few characters that isn't tainted by TDKR. He remains separated, and in doing so, it sort of acts as this brick wall that separates The Dark Knight from TDKR.