| The subject of this article has no official name.|
It is a fan-given name as substitute for lack thereof, and should not be considered as part of the Attack on Titan universe.
Armin's grandfather was an older man with a rather youthful face; yet he had a very aged body and hands. He had light brown eyes and shaggy brown hair with a beard and mustache that did not connect around his mouth. He was only ever seen wearing a tattered light brown hat, a faded beige sweater with a brown shirt over it and a green scarf, short gray pants, and shoes.
Armin's grandfather appeared to be a caring man, taking in his grandson when he was orphaned. He spoke with a calm tone and pitied Eren Jaeger and Mikasa Ackermann after seeing their horrified expressions, stating that whatever they had seen must have been terrible. Grandfather Arlelt cared for Armin and his friends, convincing the soldiers distributing food in Wall Rose to give him extra for the children.
Before the fall of Wall Maria, Armin's grandfather possessed a book containing illegal information about the world beyond the Walls. He gave this book to his grandson, Armin Arlelt, who showed it to his best friend Eren, kindling his desire to see the outside world.
In the year 845, he had been taking care of Armin until the Colossal Titan's first appearance in Shiganshina District. During this time, he and his grandson were able to board a boat and escape to Wall Rose. He continued to look after Armin and his friends, getting them food and working alongside them. He stayed as a refugee in Wall Rose for a year working the fields for food, until the royal government began a retrieval operation in 846 in order to take back Wall Maria. He was summoned to be a part of this mission along with two hundred fifty thousand other people, of which only a little over one hundred survived, himself not among them. He and the others that had died during the operation were recognized silently by the people for their help in alleviating the food shortage for the rest of the Wall Maria refugees. Before his leave, he gave his grandson Armin the hat he had always worn. After hearing the news of his grandfather's death, Armin is seen crying as he holds his hat in his hands. As his friend Eren Jaeger tells him and Mikasa Ackermann that he plans to join the military. Armin then bravely states that he is joining too, clearly upset at the government pushing his grandfather to his death. Their friend Mikasa states that she too will join and the three go into training together the following year in 847.
During his intimidation, or "rite of passage," from Instructor Keith Sadies, Armin states his name and is insulted by the instructor for it. When Sadies asks him if his parents gave him the name Armin replies that it was given to him by his grandfather.
When Commander Dot Pyxis is giving his orders to the Garrison and cadet soldiers to retake Trost District, he mentions the royal government's attempt to retake Wall Maria four years ago. When speaking about it, he directly says that it was no more than their way of dealing with being unable to feed the refugees and that by sending them outside of the Walls, they were able to survive within them. He states that all of humanity bears the weight of that sin as Armin listens in the crowd, remembering his tears and last moments with his grandfather.
- Grandfather Arlelt and Pastor Nick share the same English voice actor.