While Hulk's son Hiro-Kala was ultimately able to enslave him and turn him into an even more devastating cosmic weapon. While Galactus only ever destroys one world at a time, Hiro-Kala found a way to use him to destroy an untold number of planets. In the process, he would also have destroyed Galactus himself.
Hiro-Kala is one of the two sons of Hulk and Caiera, son of Hulk’s villainous tendencies make his meteoric rise an incredible threat. And in the Realm of Kings event, it was revealed that he was destined to destroy countless planets.
In Realm of Kings: Son of Hulk #4, written by Scott Reed and drawn by Miguel Munera, the Enigma Force Nullifier reveals to explorer Arcturus Rann the future that Hiro-Kala will enact if he is not stopped - one that had been hinted at in earlier issues as Galactus communicated back through time. Hiro-Kala is shown having poisoned and enslaved Galactus, turning him into a receptacle for the Old Power. This combined with Galactus’ own stores of the Power Cosmic - built up in his body over the course of millennia - turns the former Eater of Worlds into a powder keg. Hiro-Kala detonates him, wiping out thousands of planets containing the Old Power. This in essence would bring ruin to the entire realm known as the Microverse.
This event would be a crowning achievement for Hiro-Kala. Not only would he be one of the most powerful entities in Marvel Comics, he also would have gotten revenge on Galactus for the destruction of his homeworld. He would also finally step out of the shadow of his father and claim his place as one of the most destructive beings in the universe. Given his history of being unknown to his other family , becoming such a preeminent figure would likely solve a lot of his familial baggage, as well as fulfill his mission of eliminating the Old Power from reality.
Thankfully, this future was averted in the main Marvel Universe thanks to Arcturus Rann's foreknowledge, which he used to split the timeline off to a new future by facing Hiro-Kala. Nevertheless, Hiro-Kala's incredible power confirmed that the Hulk's forgotten son was even more powerful and dangerous than his father, and capable of not just making Galactus deadlier than ever, but destroying him soon after.
Hiro-Kala's story is a tragedy of epic proportions, and his intentions for the World Devourer showed that he was more than capable of assuming his father's "World Breaker" title. Hulk's son was destined to become one of the most dangerous beings in the Marvel Universe, and while comic fans are more familiar with his brother Skaar, Hiro-Kala is the one who truly spells doom for anyone foolish enough to cross him, even if they possess the godlike power of Galactus.
