Although both Batmen were founding members of their parallel planets' prime protectors, their relationship with their allies was at times strained indeed. Months after the Justice League's founding, Earth-One's Batman found his niche on the team and was active throughout its various cases until an uprising in the nation of Monrovia threatened his old friend Lucius Fox. When the League wouldn't aid him in saving Fox, Batman left the team to form his own, the Outsiders.
His counterpart on Earth-Two had immediately chose to be an honorary member of the Justice Society of America, like his best friend Superman. After which, Batman only joined the team on cases involving Ian Karkull, the "Five Drowned Men" and the Society's attack on Nazi Germany which time erased. However, Batman, was more active alongside the All-Star Squadron, operating around the same time period. Although aiding the Society on one adventure to Earth-S, afterwards as Commissioner Bruce Wayne he allowed his vendetta (caused by the influence of Psycho-Pirate and the effects of his advance-stages cancer) versus the Justice Society to cause a war within itself. Later he wrote a disparaging diary which held clues to the reemgence of their old foe Per Degaton, and finally he gave his life to protect his allies against the machninations of Bill Jensen and Frederick Vaux... which showed that he like his twin had deep down cared for his fearless friends.