Eren and Zeke Jaeger's trip down memory lane provides the perfect excuse for cameos from some long-gone Attack on Titan favorites. When Attack on Titan episode 79 begins, Zeke Jaeger has seized control of the Founding Titan. Determined that Eren will share his childhood trauma, Zeke insists the Jaeger brothers use Ymir's power to explore the memories of their father, Grisha. Essentially, this means Eren and Zeke stroll around observing key events from Attack on Titan history - Grisha's first discovery of the Reiss cavern, writing a fateful message in the family's basement, the day Grisha obtained the Founding Titan, etc.
This forensic examination of Grisha Jaeger's past means reuniting with some familiar faces. Aside from Grisha himself, Attack on Titan episode 79's flashbacks prominently feature Carla Jaeger, Eren's late mother, killed by the jealous ex from hell. Young Eren is shown too - both as a newborn baby, and the fresh-faced protagonist introduced in Attack on Titan season 1 - and he's accompanied by a long-haired Mikasa alongside a baby-faced Armin. When Eren whispers in his father's ear, Grisha then sees (in rapid succession) fellow Restorationists Dina Fritz, Eren Kruger and Grice, as well as his little sister and the Marleyan soldier who murdered her.
Attack on Titan episode 79 is generous with nods to the past, but two fan-favorite cameos stand out - Kenny Ackerman and Hannes. First up is Hannes, the perma-drunk Shiganshina Garrison soldier who befriended the Jaeger family and became something of a surrogate uncle to Eren and Mikasa. Hannes' cameo comes shortly after Eren and Zeke watch their father tending to a wealthy bed-ridden patient, and the semi-useless soldier can be spotted playfully dangling a wine bottle in front of a very young Eren. In the next memory, the Jaeger brothers watch as Grisha attracts the curiosity of a certain Kenny Ackerman - Levi's uncle. Both Kenny and Hannes died some time ago in Attack on Titan. Hannes was killed by a Titanized Dina Fritz during Attack on Titan season 2's finale, while Kenny perished during Attack on Titan season 3's cavern battle, caught in the blast of Rod Reiss' Titan transformation.
Both cameos serve their own unique purpose in Attack on Titan episode 79. The glimpse of Hannes serves as a reminder of innocent times, when soldiers could drink on the job and get to know local families without having to worry about invaders from outside the walls. Watching Hannes mess around with Eren not only highlights how far Paradis Island has come since those early days, but speaks to how drastically Eren himself has changed. The young kid who endeared himself to soldiers is now plotting against innocent folks exactly like Hannes.
Kenny Ackerman's cameo in Attack on Titan episode 79 subtly explains Grisha's secret mission inside the three Walls. In one of the earliest memories Eren and Zeke visit, they spy Grisha visiting a wealthy patient. The elder of the Jaeger brothers describes how their father exploited his profession as a doctor to gain information about the King from powerful politicians and influential nobles. Several memories later, Eren and Zeke watch Grisha rifling through a draw. Looking at the wallpaper and curtains, this is the same wealthy patient from before, meaning Grisha sneaked into the sick man's home under the guise of being a doctor, then stole secret documents pertaining to the Reiss family's lineage. In all likelihood, Grisha sedated/euthanized the man so he wouldn't wake up and notice his doctor rummaging around.
When Grisha passes Kenny in the next memory, the hallway is still lined with the same patterned wallpaper as before, meaning Levi's uncle was guarding the same building Grisha infiltrated. Kenny was working for the Military Police as Uri Reiss' bodyguard at this point, suggesting Grisha's patient could be a member of the Reiss household, which would explain why the doctor finds documents pointing toward the secret church's underground cavern. Kenny was clearly suspicious, but never pursued that gut instinct.
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