As a superhero and a detective, Batman prefers to work alone. But when he is confronted with a case beyond his abilities, the Dark Knight calls for help, although often reluctantly.
With allies including the Bat Family, Alfred, the Justice League, Commissioner Gordon, and Ace the Bat-Hound, it's seems like Batman has the pick of the litter when he requires assistance.
But there are situations where the cowled crimefighter has been forced to align with someone against his wishes. Sometimes, he doesn't want to ally with someone because they're immature, incompetent, or just annoying.
But other times, Batman has grievances with his partner because they are a criminal. And not just any criminal. Over the years, Bats has collaborated with psychopaths, genocidal alchemists, and mass-murdering dictators. Even though he hates working with the same scumbags he had dedicated his life to putting behind bars, the Caped Crusader is forced to do what is needed for the greater good.
If you thought Batman would never be on the same side as Ra's Al Ghul, Poison Ivy, or the Riddler, guess again.
10. The Riddler - Detective Comics #822-828 (2006-2007)
Every once in a while, a supervillain will discard their criminal lifestyle and become a force for good. There are many reasons why characters reform like this. Sometimes, it's because they learn the error of their ways. Other times, they are forced to ally with their enemies to defeat a greater foe.
But, in the case of the Riddler, all it took was a bonk on the head. After being struck by the Shining Knight, Edward Nygma was was left with brain damage and slipped into a coma. When he came to, he realised he'd been cured of his obsession with riddles and any desire for committing crimes. With his new lease on life, the cane-twirling puzzler became a private detective.
Although Batman didn't trust him, he had to work with his former foe after the Riddler learned someone was trying to frame Bruce Wayne for murder. While driving in the Batmobile, Nygma pointed out that it was the first time he had been inside Batman's car while conscious.
Even thought Bats acknowledged that he and Nygma did some good work together, it wasn't long before the bowler-sporting criminal reverted to his supervillain persona.