WARNING: The following contains minor spoilers for the Attack on Titan manga, available in English from Kodansha.
Along with introducing new characters and confirming a time jump, the Season 4 trailer of Attack on Titan parallels the Season 1 premiere of the anime before flipping it on its head. The trailer opens with Falco, one of the new characters, laying injured on a battlefield and reaching out towards a bird, wishing for it to fly away from this place. Similarly, Season 1 starts with Eren watching two geese fly free from the walls moments before the Colossal Titan demolishes Shiganshina. In both cases, these kids are faced with horrific events and long for freedom; however, one is presented with a clearly human threat, and the other, Eren, is presented with something he once thought was inhuman.
The similarities do not end there, with the last third of the Season 4 trailer showing Eren's titan attacking a city, just like the Colossal Titan did to his hometown years ago. Where this differs from Season 1 is that, unlike the Colossal Titan who had an army of mindless titans, Eren seems to be the only titan in the city fighting for his cause. The other titans featured here are either established enemies, like the Cart Titan and Armored Titan, or they're new titans, like the War Hammer Titan, who's seen attacking Eren.
What further cements Eren and his titan in a more horrific light is the poster for Season 4. Where Season 1 sees Eren, his friends, and his neighbors tremble in fear as the Colossal Titan towers over their city, Season 4 shows Reiner in the rubble of his town looking up as Eren looms over him. This poster is even similar to Season 1 Part 1's poster, which has Eren standing in a burning town as the Colossal Titan looks over the wall, and Season 1 Part 2's poster, which has Mikasa standing before the Female Titan within the walls. However, unlike these posters, which have the protagonists ready to fight, Season 4's poster has Reiner without any weapons, and his stance is weak, not proud, and strong like Mikasa and Eren's.
Furthermore, while Season 1's posters show destruction, they lack casualties. Season 4's poster, on the other hand, has two bloodied and most likely dead bodies. Eren's titan even has blood covering his hand, which is ready to strike down on the city once more. This poster commits to depicting Eren as a killer. With Reiner as the focus of this poster, as well as Eren's Titan being a murderer in the trailer and this promotional image, Season 4 could see a shift in perspective.
What furthers this is the fact that the poster features what appears to be the Scouts, based on their new uniforms from the trailer, backing Eren. However, where past posters have shown their faces, this poster has them looming in the shadows, making them more ominous and threatening, especially with Eren's Titan behind them.
As the last season of Attack on Titan, fans are bound to be in for a wild ride. The anime is not one to pull punches when it comes to death, and a lot of its lead characters have already proven to be morally questionable, regardless of how well-meaning their motives are. With Eren's titan on a rampage and the accompanying poster putting him in a similar light as the Colossal Titan, the finale of this anime is bound to have audiences question how good this protagonist truly is.
Attack on Titan Season 4 is scheduled to release in this fall.