At first look, Attack on Titan and Trigun Stampede don’t appear to have much in common. After all, one tells the tale of a human who battles other giants by changing into a giant, and the other tells the tale of a carefree gunman who can shoot through anything. But if you delve deeper and lift the layers, you’ll start to notice some parallels between the two tales.
The narrative of Eren and his friends grows considerably more intricate and darker in the last season of Attack on Titan. You witness the extent Eren would go to in order to get his revenge as well as the centuries-long mistreatment the Eldian people have endured at the hands of the Marleyans. It becomes difficult to identify who the real good person and bad guy in the narrative are at that moment. Both act for legitimate causes, and they both fight to the death to save their own people.
It may not be as intricate as Attack on Titan, but Trigun Stampede also features a similar mechanic. As was already established, Nai views humans as the entity that continuously mistreats his people, and his ambition is to essentially build a utopia for them. Despite the fact that humans are completely dependent on the plants, he observes how little humanity cares about the plants’ welfare. Therefore, eliminating the root of the issue is, in his opinion, the only way to ensure the prosperity of his people. Vash may not agree with Nai’s approach to realizing his ideal, but even the peace-loving man is powerless to ignore the horrors civilization has inflicted upon his people. Simply put, he is ready to give them another go, something Nai would never do.
Thus, in a way, the fight between the two opposing forces that merely wish to improve the lot of their people is the central theme of both shows. Should you enjoy that aspect of Trigun Stampede, the concluding season of Attack on Titan delves even farther into this specific concept.