Indeed, the classic parable, "the boy who cried wolf", has remained popular over the years due to its unique relevance.
Over the many years of Batman's struggle with the Joker, he has become all too familiar with the Joker's behavioural patterns and methods of setting up devious plots.
It's difficult for many DC comic fans to understand why, despite Batman's extensive powers, he only realizes at the last minute when the Joker compels him to make a moral choice. Shouldn't he have detected it the moment the hostages were taken?
Firstly, Batman, akin to an emperor in a feudal regime, is not exclusively focused on the Joker amidst villains aplenty in Gotham, each causing chaos in their own turn.
While the Joker is discreetly causing trouble, some villains are already staging horrific crimes, and Batman would naturally choose to stop the most dangerous ones first.
Secondly, before the Joker decides to prepare a grand feast, must create some appetizers to attract Batman's attention or run two different schemes concurrently in secret.
No matter which scheme Batman investigates, the Joker can turn the other into a feast to serve to Batman later on. Even though it appears that Batman is always a step behind the Joker, he may have already thwarted dozens of plots along the way.
Batman has been through this too many times, so he, of course, assumes that the Joker has once again set up a tricky situation to mess with his mind.
Batman reasoned that the apparent victims of the Joker's plot this time were Spider Man, as not long after Spider Man appeared, the Joker injected him with the concentrated Dark Source Elixir obtained from Gotham's rainwater, intending to corrupt him and pit him against Batman.
However, this is only the Joker's temporary plan; the trap he had laid much earlier targets the regular visitors to Gotham, the Robins.
The only possibilities that Batman can consider in this situation lead nowhere. After all, why would the Batman family create a massive bomb to destroy Gotham?
What is the point? How could they have changed so suddenly in such a short time? No matter who thinks about it, the likelihood is incredibly slim, almost non-existent.
This brings us to Batman's stereotyped impression of the cosmos where Shiller resides. Or it's perhaps not fair to call it a stereotype. All the Gothams in the multiverse are unique in their own ways. How different could a Gotham from another cosmos be?
If they are all the same, then the Robins going there is equivalent to vacationing, and since the Gotham in Shiller's cosmos is sunnier, they should have returned more cheerful and lively. How could they suddenly want to destroy the world?
No way, not possible at all!
Yet, coincidences in this world often defy reasoning. If the Robins go suddenly mad, madness that coincidentally fits the Joker's modus operandi, Batman would naturally hold the Joker responsible. Since the Joker never anticipated he could be innocent, he left no room for vindication, he's utterly tarnished, cleaning it off is impossible.
It's like the boy in "The Boy Who Cried Wolf". He's cried wolf too many times, and not just Batman, no major villain in Gotham believes him anymore because this isn't the first time the Joker has conned and used them.
Upon hearing the Joker crying wolf, most of the Riddler, Penguin Man, Clayface, Hugo, and Black Mask simply scoffed and dismissed him. Corrupt officials, mobsters, businessmen, and policemen turned away and refused to see him at his appearance.
Ultimately, Spider Man was the only one genuinely believed the cry, "The wolf has come."
"What? Mister Joker, you're saying a villain has built a massive atomic bomb intending to obliterate this city? Why didn't you tell me sooner?!"
Spider Man anxiously grabs the Joker's sleeve and stares at him sternly. The Joker swiftly turns to Spider Man and says, "Listen, you're Spider Man, right? I have to tell you, Batman is only human, he's not omnipotent, so if he tells you everything's fine, it may not necessarily be so…"
"Of course, I never thought him omnipotent either. He must have situations he didn't foresee."
The Joker, for once, looked baffled. This was the first time he'd met a Robin who didn't hold Batman in godly reverence.
"So, tell me quickly what's going on. We can combine forces and take precautions sooner, in case a super-villain really does blow up this city!"
Hearing Spider Man's tone, the Joker takes a moment to reckon, then turns to Spider Man and says, "You seem experienced with this?"
Spider Man opens his mouth, then closes it. Finally, a bit resigned, he says: "You may not believe it, but for the past few years, I've always been trying to save the world. You wouldn't believe how many times my city got obliterated."
"Then it looks like we have something in common." The Joker immediately seems like a coaxing philosopher. He doesn't portray himself as a good man, instead he sincerely says, "In the past, I was indeed a criminal. I turned myself into the police station and confessed all my sins. You heard it too, didn't you?"