We've all seen or at least heard of the Elseworlds storyline Speeding Bullets, where Superman is born on Krypton but when his ship arrives on Earth, he is adopted by the Waynes rather than the Kents. At first, it seems like "Bruce" is just a normal child. But when a mugger murders Bruce's parents before his eyes at the age of eleven, Bruce incinerates the man with his heat vision, thereby discovering his superpowers. Terrified and ashamed, Bruce flees back to Wayne Manor and later becomes the Batman. Using his superpowers, Bruce is an extremely violent figure, and eventually comes into contact with Lex Luthor, a billionaire who went insane and suffered a tragic accident which turned him into this universe's version of the Joker. The two have many battles, and Batman ultimately comes into contact with reporter Lois Lane, who gives him the idea of becoming the more hopeful and less violent hero, Superman.
This got me thinking... what if Batman as we know him had been born on Krypton? Imagine. Jor-El and Lara have a son and decide to name him Kal. Kal lives a privileged life as the son of Krypton's foremost scientist until the age of eleven, when petty mugger Dru-Zod murders Jor-El and Lara while young Kal watches in horror. In fury, Kal lashes out, incinerating Zod with his heat vision. Fearing to become an outcast, Kal dashes home, where many years later, he reappears on the streets of Krypton as Superman. Superman attempts to be a symbol of hope and reconciliation, but soon realizes that this approach will not work in the environment of the rapidly-declining Krypton. Kal then adopts the persona of Batman and begins an all-out one man war on crime.
To me, this sounds like an Elseworlds storyline that never happened but very clearly should have. And rather than have the famous blue and red suit with the "S" emblazoned on its chest, I picture this Superman wearing a black and silver suit like the ones worn by Zod and his forces in Man of Steel with a silver bat inside the diamond rather than the symbol of a Kryptonian house.