Any comic called Superman/Batman should really be the most astounding piece of reading material since Sir Gawain and the Green Knight. And yet, sadly, DC's monthly comic about the adventures of its two most famous characters has been a bit dull for a few years now. I've been obsessing, during my rare downtime, about how I would restore Supes/Bats to its former spiffiness, if Dan DiDio was somehow afflicted with brain damage and chose to let me write it. Here are my thoughts.
First, a little bit of history of the Superman/Batman teamups. The two first joined together in 1952, and quickly learned each other's secret identities. Their monthly teamup comic, World's Finest, lasted until the mid-1980s. They were best friends, and their stories often had a sort of boys' clubhouse feel, with Robin along for the ride. Occasionally a girl like Supergirl or Batgirl would want to join the club. Or either Superman would get a new "best friend," leaving Batman to feel sad and rejected. Or some mean boys, like the Composite Superman or Anti-Batman and Anti-Superman, would show up and ruin everything. But the stories would always end with the club intact again.
And then in the mid-1980s, Frank Miller and John Byrne came up with the idea of making Superman and Batman uneasy allies, who didn't trust each other. Miller's Batman: The Dark Knight Returns ends with the two slugging it out, and Byrne's Superman: The Man Of Steel has the young Superman meeting the unsavory vigilante Batman for the first time. Batman thinks Superman's a callow boy scout, and Superman disapproves of Batman's violent methods. This is the one where Batman tells Superman that he's implanted a deadly bomb in "an innocent" that will go off if Superman tries to grab Batman... and then it turns out the bomb is actually in Batman himself, which means Batman is an innocent. I keep waiting for Superman to pat Batman on the back or brush against him accidentally. (Why couldn't Batman have just implanted the bomb in a chihuahua? Chihuahuas are people too. But maybe Batman doesn't believe chihuahuas are ever innocent.) In fact, there are approximately 1,000 DC comics from the late 1980s where Superman says that he disapproves of Batman's methods, before teaming up with him.
Now, the two are back to being friends, more or less, although Superman/Batman always shows that they have very different perspectives by giving us thought captions from both of them. Superman is bright and optimistic, Batman is dark and brooding. So occasionally, Superman will think to himself, "Wow, Bruce is so dark and brooding." And Batman will think, "Oh Clark, I could never be as optimistic and bright as you are." (It's all about the first names nowadays.) And now DC is working on a weekly Superman/Batman/Wonder Woman team-up comic, written by Kurt Busiek.
So in a nutshell, the dynamic between Batman and Superman has always been a tad cartoonish and oversimplified, based on whatever the prevailing version of Batman has been at the time. (Fun caped crusader, grim 'n' gritty avenger, or paranoid-but-brilliant member of the superhero family.) Superman hasn't changed nearly as much as Batman has.
So here's how I'd make the dynamic between Superman and Batman more interesting: I'd turn them into Lethal Weapon.
Superman is the cautious one, the straight arrow who does everything by the book despite (or because of) his almost limitless power. Batman is the crazy, out-of-control risktaker who keeps dragging Superman into situations he's not equipped for. Batman is the guy who sends Superman and himself diving into a black hole on a spaceship with one dud engine. He's the one who drags Superman and himself into a nest of trolls, whose magic weapons can hack Superman to pieces. He seems to make impulsive, rash decisions, but always turns out to have a plan. Sort of.
And yes, I know that since Grant Morrison's JLA Batman has been portrayed as the uber-control freak who always plans twenty steps ahead in every situation. But he's also the non-powered guy who dresses up in a bat costume, with his face unprotected, and jumps off rooftops into gunfire every night of the week. He's the crazed, half-suicidal Mel Gibson to Superman's Danny Glover.
Every Superman/Batman storyline should start with Superman being totally on top of things as usual, crushing a rogue giant robot with one hand while using his heat vision to stop a falling satellite from crashing on a populated area. And maybe using his super-breath to avert a tsunami at the same time. And then suddenly, Batman comes zipping up in his Bat-plane and is like, "time to go, boy scout!" Superman starts to protest, but he knows Batman only resorts to asking for his help when it's a serious problem. The next thing he knows, he's lost control over his superpowers and Batman is sending the two of them in a tailspin into a magical soul-eating volcano. "This volcano is connected to a crime that happened in Gotham City, which means it's MINE," Batman explains helpfully.
Instead of looking at Batman and thinking, "I don't approve of his methods," or "He's my pal," or "Bruce, why are you so grim and dark?" Superman should be shouting "Bruuuuuuuuuuuuuuuce! What have you gotten me into this time?" at the top of his super-lungs, while Batman cackles.