|Eren. You couldn't save your mother because you lacked the strength. And I...I couldn't stand up to the Titan because I lacked the courage!|
|— Hannes to Eren|
Hannes was a tall, well-built man with short blond hair, a thin dark mustache, and golden hazel eyes. He wore the typical uniform of the Garrison Regiment along with a gray v-neck shirt underneath.
Hannes was a very kind, good-natured man, but he often drank irresponsibly. He was greatly ashamed of his lack of courage five years ago, and cared deeply for Eren and Mikasa. He looked out for them after Carla was eaten.
Before the Fall of Wall Maria, Hannes would often sit around drinking and socializing with fellow soldiers in Shiganshina District. On one of these days, Eren Jaeger got into an aggressive fist fight with three other boys and the soldiers were called upon by a merchant to stop them. However, a drunken Hannes claimed that someone more qualified to help would be along shortly. Moments later, Mikasa Ackermann came to help Eren with Armin Arlelt trailing behind. The soldiers then cheered on the children as they fought until the merchant threw a bottle at Hugo, calling him a waste of taxes. While Hugo attempted to fight him, Hannes claimed that the merchant was speaking the truth and stopped him until the merchant hit him in the face as well. The two then engaged in a fist fight until a Military Police officer came and stopped them, causing the three boys and Eren to run off.
Hannes is first introduced as being drunk while on duty, in the Shiganshina District shortly before Wall Maria fell. He and a fellow Garrison member, Hugo, are chided by Eren, who thinks they are being reckless by drinking as the Walls could fall any day. Hannes however, is relaxed, saying that the Walls have stood for a century without a breach.
During the fall of Wall Maria and subsequent Titan invasion, Hannes arrives at the scene with Eren, Mikasa and Carla Jaeger as she is trapped underneath her house that was hit by the rubble caused by the Colossal Titan's attack. She begs him to take the children and run but he wishes to instead kill the approaching Titan and rescue Carla as well. Horrified by the distinct wide, grinning face of this Titan, Hannes saves Mikasa and Eren from certain death, despite the fact that he does not have the courage to fight the Titan that devours Carla.
Moments after the traumatizing event, Eren punches Hannes repeatedly, crying out why he could not save Carla, and Hannes throws him to the ground. Eren continues his blind efforts of attacking Hannes, with Hannes tearfully explaining that the reason Eren could not save his mother was because he lacked the strength, further infuriating Eren, but Hannes says that the reason he himself could not save Carla was because he lacked the courage. He escorts the two away from the chaos.
Hannes escorts Eren and Mikasa on the boat escaping the district and shortly after participates in the evacuation of Shiganshina. He tries to reason with the other Garrison members, saying that if they close the gate the people inside the district will be devoured, however, the other argues that the Titans will invade the entirety of Wall Maria if they do not. Hannes attempts to stop the command, but the conflict is short-lived as an Armored Titan breaks through the Shiganshina gate, and Hannes watches in horror of the aftermath of the blow.
Hannes meets Eren, Mikasa, and Armin again five years later in Trost District and compliments them for graduating from the Cadet Corps, as Eren compliments him for earning the rank of Captain. After fooling around a bit, Hannes becomes serious and apologizes for not being able to save Eren's mother. However, Eren does not blame him for this, and claims that they will never let a tragedy like that happen again, before running off. Hannes briefly thinks to himself, wondering if he should be happy that Eren has grown up. He then wishes for him not to die.
After Trost District is attacked by the Colossal Titan and breaks down, Hannes' squad takes up positions atop Wall Rose to serve as lookouts, in case the Colossal Titan returns. As Hannes admires the harpoons that were set up to catch any Titans near the wall, his subordinate Phil expresses his fear for their comrades, reminding Hannes that Eren, Armin, and Mikasa are members of the vanguard. Hannes calmly tells Phil that he is sure all three are still alive.
As Hannes works on the cannons mounted on the Walls and sees Eren walking with Commander Pyxis. Seeing this, he feels relief that Eren is okay and survived fighting inside Trost. Eren signals to him to focus on his work, annoying Hannes that Eren would dare talk to a superior officer that way. Hannes deduces from Eren's demeanor that Mikasa and Armin are also alright, and begins to wonder why Eren is walking with the commander as they leave.
Hannes appears once more apparently giving a report to Pyxis when a Garrison member bursts in and informs them that Wall Rose has been breached. He is the commander of the Wall Rose counter squad and heads out to find the breach. Hannes is surprised to find no sign of a breach and in fact no Titans near the Wall itself. After relaying this information to Hange Zoë, who is equally surprised, he begins to leave.
Hannes is unable to leave because he becomes involved in the battle with the revealed Armored Titan and Colossal Titan. He expresses shock once he sees the Colossal Titan atop the wall and angrily wonders why it showed up there. He asks Historia about Eren and she points towards the other side of the wall. Hannes is surprised when he sees Eren's Titan form for the first time. After the Armored Titan roars, Hannes watches in horror as the Colossal Titan starts to fall off the wall.
After the blast caused by the Colossal Titan's impact, Hannes watches over the injured soldiers atop the Wall. He returns with some rations, giving some to Armin and Mikasa, remarking that they are often the ones to get Eren out of the situations he finds himself in. He recalls that Eren has always charged head-on into his fights, regardless of how outnumbered he was. However, while Hannes had never seen Eren win a fight, he never saw him give up when beaten.
Hannes grows nostalgic for the days he used to share with the others before the fall, days which he believes Eren would consider a false peace. Desiring to return to those peaceful days, Hannes agrees to join Mikasa and Armin in their mission to rescue Eren from the traitors.
Hannes is among the many soldiers who take part in the operation to rescue Eren from Reiner Braun and Bertholdt Hoover. After Eren is retrieved and the Smiling Titan appears, Hannes steps in to protect Mikasa and Eren. He engages the Smiling Titan in battle, and after a while, is caught. Neither Eren nor Mikasa can do anything to stop it, and Hannes' entire lower half is severed, tearing his spinal cord, killing him.
- Carla Jaeger - For unknown reasons, he owed Carla a debt. While Carla is trapped, he tried to make good on the debt by saving her and her family, Carla pleaded with him to save her family instead. He attempted to slay the Smiling Titan but lacked the courage, he grabbed Eren and Mikasa and decided to run, and Carla thanked him for doing the right thing. He still felt guilty about leaving her. Years later, he made good on the debt by saving Eren's life by engaging the Smiling Titan, and died in the process.
- Eren Jaeger - Fired up, capable, stubborn and persistent that scared him, Eren did not resent Hannes for not saving his mother. Eren shared memories of more peaceful times with him and which he could go back to that time.
- Mikasa Ackermann - He admired her toughness and referred to as the best fighter he ever saw. He saved her life along with Eren's on two occasions. He also shared memories of more peaceful times with her.
- Armin Arlelt - He admired his intelligence and referred to Armin as extremely intelligent. He also shared memories of more peaceful times with him.