...one, the last son of doomed planet Krypton, rocketed to Earth to be bright, shining symbol of hope for the city of Metropolis...
...the other, the son of wealthy parents, taken from him in a horrible crime, dedicating himself to a war against all criminals in his home city of Gotham.
Superman and Batman - Brothers
The Kents took in young billionaire Bruce Wayne to care for him (and Superboy thought Bruce on his way to becoming a criminal...until he learned the truth...as Bruce had become...Batboy!).
Superboy and Batboy continued their partnership through adulthood (and Bruce getting full control over his parents' fortune and Wayne Manor). Bruce and Clark moved to Gotham (with Clark becoming a reporter for the Gotham Gazette)...at least until they cross paths with Lex Luthor...and he kills the Kents!
....with Batman barely able to not kill Luthor!
For the good of the world, Superman takes Batman to the 30th Century to work with the adult Legion of Super-Heroes, while Superman stays behind to protect 20th Century Gotham and run the Wayne Foundation!