There’s a gag that’s been running through Batman comics for as long as I can remember. Batman and Commissioner Gordon are engaged in a terse discussion over Gotham’s latest batch of murders. Batman then disappears mid-conversation, leaving poor Gordon talking to himself by the light of the Bat-Signal.

Every writer seems to have provided their own variation on this same vanishing act, but only one I know of explains why Batman does it.

Before I get to that, though, a little more on my last mention of the “tangle of personal tragedies and pointless minutia” of some comic book continuity. Company-wide reboots like Crisis On Infinite Earths are one way to fix these snags, but more common is to perform on-the-fly ‘battlefield surgery’ on continuity hiccups. Writers create new justifications for odd notions from previous issues as they go – or, at worst, they find new excuses to ignore the weirder or dumber elements of their characters.

Geoff Johns’ work on Green Lantern is dedicated to this conceptual surgery. He took the fact that Green Lantern’s ring originally didn’t work against the colour yellow – a random weakness introduced to give villains a shot at winning – and transmuted it into an all-encompassing, world-building logic for his corner of the DC Universe.

He’s created a sci-fi “emotional spectrum” of warring colours that explains early Green Lantern stories while also providing endless fodder for later ones. Admittedly, I’m still waiting for him to tackle the time Green Lantern fought The Shark despite his invisible yellow forcefield. (Yes. You heard me. Invisible and yellow.)

Sometimes a retroactive justification can be much smaller in scale. Greg Rucka wrote an idiosyncratic Batman story called “Falling Back” in Legends of the Dark Knight #125. It came towards the end of a sprawling crossover called “No Man’s Land” – a surprisingly good crossover, too. Even when it was leaking logic it was full of fascinating ideas and dark character turns.

Gordon is upset that a defeated Batman disappeared, abandoning Gotham. Now that Batman’s back, Gordon wants nothing to do with him. He’s furious that Batman left the city unprotected without even a word; furious that no one in law enforcement will take him seriously because he needs a masked vigilante to help him.

They finally meet, face to face. This issue is almost entirely dedicated to their conversation: no fight scenes, no flashbacks. Artist Rick Burchett lets whole pages sit, empty of dialogue, as these two men struggle to find the right words. Downstairs, a waiting Robin nervously says it feels like his parents are deciding if “the divorce is final”.

When Batman tells Gordon that they’re still partners, Gordon responds: “Partners are equal, Batman! When have you ever treated me like your equal? Partners, for example, tell you their plans! They keep you informed! And they sure as hell don’t walk out on you in the middle of a sentence!”

Batman slowly bows his head, and says: “I’ve never been good at saying goodbye.”

Batman’s disappearances aren’t just him being needlessly spooky; it’s that he’s still so consumed with guilt and grief over his parents’ murder that he’d rather vanish than risk another goodbye.

And, just like that, a tired gag is injected with retroactive heartbreak.