I get what you are going for, but you're wrong here.
Batman doesn't kill the Joker because narratively, we need to have more conflict with Batman and his dark mirror he doesn't have any right to do so. He stops the Joker and turns him over the legal system who tosses him into Arkham for the 584th time instead of forcing congress to pass "Joker's Law" that imposes a three-strikes system of anyone who poisons an entire metro area, and on your third strike you are executed regardless of mental fitness.
Bruce knows that if he starts becoming his own judicial system, its only a short slide to becoming a true force of evil.
So Batman doesn't bare any responsibility for the Joker escaping (again), its the legal system that has failed.
I perhaps worded it wrong
"Why doesnt ANYONE kill the joker?"
Except people say that Batman should be the one to do it because he is the one that constantly puts the clown in Arkham and expects him to not escape and do it again. Its something the batman brand is actually pretty aware of it and it always struggles at giving a somewhat acceptable explanation as to why, if Batman doesnt do it (again for legal reasons and because Batman knows he might turn into a VERY dangerous threat if he ever crosses that line, which I recall The Batman Who Laughs and his crew were mostly about), why doesnt ANYONE ELSE does it? There are so many murderers and hired guns in DC alone, how come none of them ever decided to put a cap on the clown's head ? (outside of obvious plot armor, "Joker Immunity" as they put it). And then there is the legal system that, apparently, just accepts the joker gets locked up in Arkham over and over, escapes and commits attrocities that would make most terrorists blush. Even if they kept buying the insanity talk, you would think eventually someone would come up with a legal loophole to declare the joker more than liable for the death penalty. Its just something you arent suppose to think about it too much because The Joker is such an engaging villain that not having him around would be missed.
I don’t think Vader really believes he can overthrow the emperor. The effort with Galen Marek was a fraud, and none of his other endeavors were really serious about it.
If he has any hope of overthrowing Palpatine, it’s in a vague future behind the hills(that will never come) sort of way.
More like the stuff with Galen (again, going with EU vader here) was the evidence that just training someone to be strong enough wasnt going to work since Palpatine would catch on sooner or later. Luke was going to have to do it because he didnt want to destroy him and he was able to convince he could join them...tho if he thought that Palpy was ditching the rule of two (which is something he wasnt a particular fan of) or not, it wasnt clear.
But we could say that Vader's "Plans" to destroy palpatine were mostly pipe dreams and cooping mechanisms. Vader wanted to kill Palpatine for all he had done (tho there was also some ambition of ruling the galaxy himself too) but he knew that at his state, inside a suit PALPATINE designed so his force lightning will be extra effective, facing Palpatine was suicide.
Then again, Palpatine made it very clear he didnt intend on Vader killing him to keep the Rule of Two going, as he intended to achieve immortality, thus that rule would be worthless.
Vader OTOH as others have said... well, he was supposed to be two characters, and Lucas merged them. So the character has a bit of D.I.D. baked in the core. But Vader as a character stopped making sense to me post-Prequels. Even as someone driven by self-loathing, or working 'on the inside' to stop the emperor or w/e, it doesn't make sense to be the Emperor's #1 assistant manager best troubleshooter working for the guy who killed all your friends and made you kill a room full of kids.
Again, that aspect of the prequels feels like needed more re-writes because Anakin barely shows that "good" within him when becoming vader. Like I said, him sparing the children (probably claiming they are "No threat without their masters to teach them") and the clones saying "nope! Murder!" and shoot them all down while Anakin just walks away emotionally frustrated would have been more powerful. It shows that he is in the dark side, yeah, but he still has that good within him that has lines he isnt willing to cross (at least not until he becomes suited Vader). Either change the child murdering scene or just dont have it altogether, just have a passing dialogue from the clones to Anakin and say the "younglings were dealt with" with him probably reacting with a silent frustrated stare before he looks away, as if to say "Fuck, I know there is no turning back now but by God I wish there was..."
I also think the dialogue with Padme at Mustafar needed another rewrite (George Lucas himself admitted writing dialogue isnt his strongest suit). He needed to show more anguish over he is doing and trying to convince himself that he is on the right but hard path. Maybe he is close to becoming Vader evil but Padme is able to shatter that and bring him back down to Anakin again. Him throwing the "And we can rule together" dialogue felt out of place and perhaps a pointless call back to Empire. He should have made it clear that he is doing this for them and their child's future and that, altho he may hate it, its a "necessary" evil. Again, there were better versions of that scene, maybe he is close to agreeing with Padme, maybe kissing together to seal it when he sees Obi-Wan and Vader comes back tenfold.
They didnt portray the struggle that would get buried by Vader's apathy and hatred for everything that is (including himself), that only Luke's love was able to bring it back to the surface. Ep 3 should have been about the downfall but how there is still hope buried within Vader's dark heart that someone he has attachment could still bring it out, hence Padme's last words being that there was still good in him.
Again, this is mostly on George's fault.
Needa went to personally report to Vader, took full responsibility, and got choked out.
Which tbf, Needa's execution really felt out of place.
You can make the argument that Vader was particularly in a VERY bad mood because of his frustration at not finding Luke. So he really didnt feel like letting him go with a stern warning or a non fatal choking. He really wanted to send across he is seeing red and to not even THINK to mess up even a tiny bit or else its choking time for ya.
Vader actually tended to punish via execution those people not only if they screwed up due to incompetence, but if they tried to blame others for it. If you owned up to the screw up, he'd likely just let you live after scaring you shitless and extracting an oath to do better. People forget Darth Vader was a pretty good boss by bad guy standards.
Depends on the writer honestly...
Sometimes Vader is a decent boss to be under if you keep your head low, show him respect and loyalty and do your part.
Sometimes he is a murderous maniac that kills you if he is feeling bored or if you wronged him slightly on accident.
One could say that makes him somewhat realistic given his living condition
I say its inconsistent writing that comes from having several writers over the years
