Batman and Captain America formed a bond due to their shared experience of losing their respective sidekicks, Jason Todd and Bucky Barnes. For decades, both heroes carried the emotional burden of their sidekicks' deaths, deeply comprehending each other's anguish. Their encounter took place amidst a fierce battle between the Justice League and the Avengers.

At first glance, Marvel's Captain America and DC's Batman seem worlds apart, yet they unexpectedly share a profound trauma.
Batman, once a privileged youth with a doting family, had everything snatched away by a single, brutal criminal act. Conversely, Captain America began as a patriotic young man who aspired to serve his country, enlisting in the military to combat Nazis during World War II. Despite their seemingly disparate backgrounds, a surprising common trauma unexpectedly binds these heroes.
In the events unfolded in the JLA/Avengers miniseries crafted by Kurt Busiek, George Perez, Tom Smith, and Comicraft, the barriers between the DC and Marvel Universes shatter, allowing characters to cross into each other's worlds. During a pivotal clash between the Justice League and the Avengers, Batman and Captain America cross paths, leading to a startling revelation for Cap.
As Batman and Captain America engage in a skills test, they gradually recognize each other as comrades. Seeking to uncover the truth behind the tampering of their universes, Batman escorts Captain America to the Batcave. There, Cap makes a profound discovery: the tragic loss of a sidekick, a shared sorrow that binds them together.
When it comes to the Justice League's ability to protect themselves and others, ten standout defensive powers have emerged as the most effective in the team's illustrious history. Notably, Batman and Captain America, two iconic heroes, have both endured the heartbreaking loss of their loyal sidekicks.
One of Batman's biggest failures as a hero was losing Jason Todd. Jason, a young boy struggling on the streets of Gotham, was taken in by Batman and given the role of Robin. He gladly accepted, and they fought crime together until the Joker tragically killed him. This devastating loss haunted Batman for almost two decades. Although Jason later returned, his relationship with Batman was forever changed. This profound trauma is not fully understood by many DC heroes, but Captain America can relate.
Captain America, a pioneer superhero in the Marvel Universe, had a close friend and sidekick, James "Bucky" Barnes. Barnes, a skilled military operative, trained worldwide before being paired with Steve Rogers. Discovering Rogers' secret identity as Captain America, Barnes stepped into his own superhero role, fighting against the Hitler Youth. Despite his cynicism, he always strived to embody Captain America's ideals, ultimately sacrificing himself in a plane explosion after confronting the Nazi scientist Zemo.
Interestingly, both Jason Todd and Bucky Barnes returned to their respective universes, transformed into the anti-heroes Red Hood and the Winter Soldier. Captain America, having experienced similar loss, understands Batman's trauma more deeply than most.
Although Jason Todd and Bucky Barnes eventually came back to life, they were both presumed dead for a significant period. For decades after their demise, Jason and Bucky remained absent, leaving Batman and Captain America to bear the scars of their loss. Batman, who seldom speaks of his failures, channels his trauma into motivation, yet the loss of Jason Todd proved to be his most devastating experience since the passing of his parents. Similarly, Captain America, who fought in the worst war humanity has ever witnessed, carried the heavy burden of losing Bucky Barnes for years. The crossover comic JLA/Avengers is now available from DC and Marvel Comics for your reading pleasure!