Kenny's grandfather

Grandfather Ackerman was the grandfather of Kenny and Kuchel Ackerman, and the great grandfather of Levi Ackerman. He was one of the few living remnants of the Ackerman bloodline with knowledge about the reasons of the persecution of his clan.

Appearance
He was a sickly and frail old man, with limp, light colored, neck length hair. He had weary eyes, a pointed nose, and a mustache that formed into a beard. Due to his health, he wore loose fitting clothes and appeared unable to leave his bed.

Personality
In an attempt to protect current and future members of the Ackerman family, he intended to die without ever telling anyone the secrets of the Ackerman bloodline's previous life by the King's side.

The Uprising arc
On his deathbed, Kenny Ackerman visits him, for what will likely be the last time. He tells him that he found his sister, Kuchel Ackerman, and that was impregnated by a customer. He also informs him that the Military Police that were snooping around have been taken care of.

Baffled at the state the Ackerman family is in, he questions his grandfather about how things came to be that way. In an attempt to sweet talk him he goes on to say, "I'm your cute little grandson, aren't I?" Gasping, he sits up and asks if the cute little grandson he knew is known in the capital as "Kenny the Ripper." Though originally intended to keep the Ackerman secrets to himself, seeing the state that the Ackerman family is currently in, he begins telling Kenny what he knows.

He starts off by clarifying that the royal government doesn't hate the Ackermans, but fears them instead. Due to the King's inability to control them. He goes on to say that despite being born within the Walls, he is certain that they served at the core of the royal government; with the duty of ensuring humanity's continued survival. He mentions how most of humanity if from a single bloodline, while a small group is from separate bloodlines. Because of the those from the differing bloodlines, they posed a threat to his rule, the king was unable to see his ideals come to fruition.

The King's ideal rule was to rewrite humanity's memories by erasing the history of the past in order to bring about peace and order. When Kenny becomes confused at the mention of erasing memories, grandpa Ackerman flatly states that it's the Titan's power. Maintained by the monarchy, the Titan's power has been passed down from generation to generation. A power so strong, it was used to create the walls, and erase the history of life outside them for the vast majority. Despite this, it has limitations, and has no effect on the minority bloodlines; including the Ackermans. So in order for the King's ideals to be realized, the minority bloodlines needed to be, in some way, silenced. Only two of the bloodlines opposed the King, they gave up their positions and turned their backs on the royal government.

He goes on to say that originally the truth was kept from his generation as well, in an attempt to protect them. But those before him gave up their life in to preserve the lives of remaining members of the Ackerman family. For a moment Kenny is silent, he decides he believe his grandfather's story; because it'll be more fun that way.