Thunderbolt Ross' transformation into Red Hulk is one of those comic book twists that feels both shocking and inevitable. I mean, the guy spent years obsessing over the Hulk, trying to destroy him, only to become a version of the very thing he hated. It happened in 'Hulk Vol 2 #1' (2008), where a shady group called the Intelligencia—led by MODOK and others—exposed Ross to gamma radiation, but with a twist. They combined it with a super-soldier serum, turning him into a red-skinned, tactical-minded Hulk with all the rage but none of Banner's moral conflicts.
What I love about this arc is the irony. Ross, the military hardliner who saw the Hulk as a weapon to be controlled, became something even less predictable. His Red Hulk persona was initially a mystery, rampaging through the Marvel Universe, even fighting Thor and absorbing his lightning attacks. Later stories explored his struggle with the monster within, especially in 'Thunderbolts' where he led a team of antiheroes. It’s a classic case of 'be careful what you wish for'—Ross got power, but at the cost of his humanity.