Throughout Avengers: Infinity War, Thanos made it abundantly clear that his mission to remove half of the population throughout the universe wasn't about killing people, but about saving future lives. Thanos attempted to convince the rulers of his home planet, Titan, that removing 50 percent of the population was the only way to save their world, but he was called crazy and driven away. When Titan was eventually featured in the movie, it was a wasteland, seemingly proving Thanos right.
What wasn't explained however, was what actually went down on Titan. Did crowding and overpopulation kill the planet? Or did something else happen?
The answer was finally revealed in Marvel's young adult novel, Thanos: Titan Consumed. The book aims to tell the story of Thanos in his early years, showing readers what led to his downfall. Of course, this touches on the downfall of Titan as well.
When Thanos realized that the planet was destined to fail, he took his findings to his father, who quickly shot him down. As we know, Thanos is pretty persistent, so he didn't stop there. After being turned away by his father, Thanos shared his findings with the rest of the planet, which caused complete chaos.
Thanos convinced the other Titans that their world was going to perish, and that the only thing they could do to save it was kill half of the population. This theory caused panic to break out around the planet. Riots took place all over the bigger cities, and many people took their own lives, as a way to sacrifice themselves for the greater good. Since he caused all of the pain, Thanos was quickly exiled.
The leaders on Titan must have thought that getting rid of Thanos would solve the problems, but they were wrong. Despite the absence of the Mad Titan, the planet still fell into despair, and its population eventually died off.
As if Thanos' story in Avengers: Infinity War wasn't tragic enough, this extra background makes things even worse.
Thanos will next appear in Avengers 4, which arrives in theaters on May 3, 2019.