-In the tv. show breaking bad the main. character named Walter white used the alias Heisenberg in order to anonymously make and sell drugs for his treatments and family welfare. As the show goes on Walter is slowly taken over by the 'Heisenberg' persona becoming colder and more brutal in his methods in his goal to building his drug empire until he becomes its largest villain. "Going full Heisenberg" means when a character. starting out with good intentions becomes an antagonist or villain over times as the plot progresses as they use increasingly brutal or cutthroat means to achieve their goals.
The way that Eren used the founding titan. trying to save Paradis , by destroying the rest of the world, he was going full Heisenberg.
by Raegan's Rock December 16, 2020