What are your thoughts on Joker and Lex Luthor's relationship (also the Batman/Superman Friendship)?
Joker taking an interest in Lex makes all the sense in the world. When it comes down to it Lex is Joker’s “type”: parental issues, extraordinary intelligence, peak physical fitness, and a self-righteous streak a mile wide.
Fucking with Lex brings all the same kind of contesting of wills and minds that messing with Batman brings, and Joker does seem to derive a similar measure of delight in undermining Lex's inflated ego. Other than screwing with Lex, when he does decide to "help" Lex in whatever new goal Lex is pursuing, Joker also gets access to Lex's resources, and gets to be part of major villainous team ups that allow him to cause chaos on a global scale. There's plausible justification for me to buy that Joker sees enough value in Lex to help him out every so often, and to keep doing so despite both of them occasionally trying to kill the other.
But what does Lex get out of the relationship?
Smart as Lex is, he sees himself as a temporarily embarrassed "hero". He truly believes that from his atrocities will come a better world which will accept Lex's justification of everything he's done having been for the greater good. So from Lex's perspective it's useful to have an unrepentant "villain" for when he needs someone to dirty their hands for him in a way he can't do himself. Joker's mind is also depraved in a way that a normal human mind, even one as intelligent as Lex, is not, and Lex can't rule out that Joker may offer a solution to a problem that Lex can't solve himself. I can buy that Lex is willing to forgive the Joker's betrayals and team up with him yet again, as long as it's made clear that Lex is always planning on killing the Joker himself once he deems Joker's usefulness at an end. He holds no hard feelings because he would, and will, do unto Joker as Joker has done unto him at the earliest opportunity.
My favorite feature of the Lex/Joker relationship is how it contrasts with the Superman/Batman one. Unlike Superman and Batman, who are very similar despite their seemingly insurmountable differences at first glance, Lex and the Joker have incompatible worldviews. The central difference between Lex and the Joker is that while both of them agree that the universe is without meaning and human life is worthless in the grand scheme of things, they differ in their response to that belief. Lex believes it's possible to force the universe to acknowledge humanity, or at least himself, as an exception to the norm of insignificance in the grand scheme of things. Joker believes that's impossible and so takes the universe's nihilism as a license to do whatever he wants without restraining himself.
In short Lex believes it's possible to overcome the cruelty of the cosmos, to force the world to make sense, and uses that as a justification to do what he wants. Joker meanwhile has succumbed to what he sees as the inherent evil of life, and justifies himself by claiming that his acts of depravity are in line with the way reality operates when stripped of the illusion of order. Lex wants to be more than he is while Joker accepts his role in life. They both may be selfish pieces of shit, but the engines driving them are on different tracks, which makes for entertaining interactions between the two, but prevents them from forming a genuine understanding between or friendship with each other.
Fitting then that their heroic counterparts have a much different relationship.
For all the superficial differences that have been thoroughly examined, Superman and Batman are more alike than they are different. Both are products of tragedy, Superman the death of Krypton, Batman the death of his parents. Both hold to personal codes of conduct that guide their actions, and will choose to follow their personal codes over the law or authority figures when those conflict with their ethics. Both have mothers named Martha and each's closest friend is a red-head named Jim. Both maintain two separate identities that exhibit different sides of themselves, both often struggle with which identity is the "real" one, and both arguably possess a third "identity" which is their true self that only their family and closest friends get to see. Finally and fundamentally both are motivated by the desire to preserve life above all else. Superman may make a big deal about inspiring others to do good, and Batman may trumpet how he's about terrifying others away from doing evil, but both are symbols of hope to those in need of justice.
It's why the two make for the best duo in superhero comics. No one else plays off each other as well as they do, because no one else was specifically built to contrast with each other. That they would team up is believable enough given they tend to be the first of their generation of heroes, regardless of whether or not any heroes came before them, and each one quickly validates his reputation to the other as being skilled and competent. They also complement each other well - Superman brings the powers, the humor, and the science fiction elements, Batman brings the detective skills, grit, and the crime elements - which is why everyone wants to see them together. You know shit is either about to get weird or serious if the situation calls for the World's Finest to team up once more.
Now when it comes to the Superman/Batman friendship one thing that always bothered me about the relationship is that each tends to have the other as an aberration in their worldview. Normally Superman sees the good in everyone, but when it comes to Bruce he tends to view everything Bruce does in a very negative light, always making grim assessments about Bruce's mental state. Meanwhile Batman is known for always being able to get into peoples heads and see how they think except with Clark. Instead he routinely underestimates Clark's intelligence, viewing him as thankfully too stupid to comprehend that many of his displays of power can come across as godlike, and at heart just a simple farmboy/Boy Scout who doesn't grasp the complexity of reality.
It didn't bother me that their relationship produced these breaks from the norm, but the why this was so always bothered me. Eventually I had two major flashes of insight: One is that Superman tends to think the worst of Batman because he sees in Bruce a second Lex. Obviously this only really makes sense for origins like Birthright where Superman knew Lex before Lex became a total asshole, but it justifies why Clark puts up with all the bullshit Bruce pulls. Clark failed Lex at a crucial moment that dissolved their friendship and put Lex on the road to becoming the supervillain he is, rather than the hero he could have been. Batman has a lot of the same paranoia, arrogance, and entitlement as Lex does, and Superman recognizes that. So even though he's never going to break completely with Batman, out of fear of creating another Lex, he can't help but see the similarities between his former friend and his current one.
Second is that Batman needs to believe Superman is an idiot because the alternative terrifies him. As long as he convinces himself that Clark is simply too dumb to ever consider that many view him as a god, and let that view affect him, then Bruce can rest easy at night. He can afford to trust Superman as a friend and a comrade if he lies to himself that Clark can't go bad because he's too simple to do evil. It's a willful ignorance on his part, one he stubbornly clings to because it's easier than trusting Clark to stay on the straight and narrow no matter the hurdles thrown up against him.
Oddly enough that each is the other's blind spot only enhances the relationship to me, because it means they bring out a different side of each other when they're together that we don't get to see when they're solo, and isn't that exactly what a team-up should aim to do?
During Harley Quinn's first week as an official Arkham prisoner, she continuously turned on the sprinklers to piss off the guards. Now she still does it but now it's so that her Darling Pamela can get enough water and not wither.
Once during a prison riot, Harvey broke his arm, it took three guards to prevent him from evening them out.
During a mass Arkham escape, Eliza once managed to sleep through the entire thing, wasn't disturbed once, and only realised that it happened because when she woke up no one was there.
Jervis once accidentally flushed 3 months' worth of fear toxin down the toilet, to this day Jonathan doesn't know that it's him.
The Arkham staff once forgot to close the elevator when they were feeding killer Croc, it was quite a surprise when it came back up with a giant lizard inside.
During Ivy's first year in Arkham, her pheromones accidentally got into the ventilation system, which was not a fun week for the guards, worked out for Ivy, she managed to escape.
Joker's no longer allowed to eat with the others, he's bitten off five noses and seven ears.
Jonathan to this day is still trying to figure out who flushed three months' worth of fear toxin down the drain, Jervis is pointing towards the Joker, evidence-less so.