Who's the strange old man speaking with Eren in Attack on Titan season 4's latest episode? A marked departure from the show's usual format, Attack On Titan season 4 continues to explore the outside world, and the repressed Eldian population living under the rule of Marley. Most of Attack on Titan's usual protagonists are nowhere to be seen, but a long-haired, injured Eren Jaeger has managed to infiltrate this foreign land under the guise of a recovering soldier. Preparing for an inevitable attack, Eren is waiting to strike behind enemy lines, and has found a useful companion in the innocent young Falco, who is ignorant as to Eren's true identity.
In Attack on Titan season 4's "From One Hand To Another," Eren is sharing another conversation with Falco, asking the boy to send secret letters to his "family." During the meeting, Eren is approached by an older man who Falco assumes to be a doctor at the hospital Eren is staying at. Falco leaves, and the newcomer begins talking to Eren, becoming increasingly animated until he's dragged off by staff. The stranger is clearly a patient, rather than a doctor, but curiously, is referred to as "Mr. Jaeger." What relation is this character to Eren Jaeger?
Although Attack on Titan never explicitly reveals the man's identity, Eren is actually meeting his paternal grandfather during this scene. Eren's mother was one of the wall Eldians, but his father, Grisha Jaeger, came to Paradis Island from Marley. The old man who approaches Eren is Grisha's father, and the clues are all in his dialogue. Aside from sharing a surname, the "doctor" has an in-depth knowledge of the Eldian Restorationists, how rebels are punished, and the system of honorary Marleyan warriors. This makes sense, as Grisha was a member of the rebellion sent to Paradis Island, and Grisha's own parents ended up caring for Zeke, who went on to become an Honorary Warrior carrying the Beast Titan. The old man knows exactly who'll inherit the Beast Titan after Zeke.
As the scene intensifies, the old man regales Eren with a tragic tale - his two children, a son and daughter, ventured outside of the Eldian internment zone and paid the price. His son also ended up in the medical profession, and while the man is taken away before finishing his story, it's clear that he'll never see his family ever again. No names are mentioned, or faces shown (other than the man himself in bygone times), but the story perfectly matches Grisha Jaeger's childhood, which was revealed in Attack on Titan season 3. The sequence also includes brief flashes and silhouettes back to those episodes without ever fully revealing the figures involved.
Although the information is all there, Eren's first on-screen meeting with his own grandfather is easy to overlook, largely because the scene is deliberately underplayed. Not only is Mr. Jaeger barely clinging to his sanity, but Attack on Titan tricks viewers into believing the man is Eren's doctor until the final moment. In truth, Eren's grandfather was once a man of medicine within the Eldian internment zone, and the white coat he still wears is likely just a remnant of the past. In flashbacks, Eren's grandfather was a hateful character who happily drank the Marleyan kool-aid at the expense of his own family, but this scene reveals he ultimately came to regret those decisions.
The strangest aspect of the conversation between Eren and his grandfather is how little Eren himself reacts. Attack on Titan's protagonist might be undercover, but anyone in Eren's situation would've shown some reaction to meeting a long-lost family member. Eren, however, is completely and genuinely unmoved, neither angry at his grandfather's past, nor elated to discover a new family member. This is the clearest indication yet that Eren Jaeger is no longer the character fans knew from previous seasons of Attack on Titan.