Armin Arlelt (アルミン・アルレルト Arumin Arureruto?) is the 15th and current commander (団長 Danchō?) of the Scout Regiment. He is also a childhood friend of Eren Jaeger and Mikasa Ackermann, and is one of the two deuteragonists of the series. Although he appears to be the physically weakest of the 104th Cadet Corps, his high intelligence and strategic genius makes him an invaluable asset, though he does not consider himself to be one and is known to have low self-esteem. After the battle of Shiganshina District, he took the power of the Titans from Bertholdt Hoover and became the Colossal Titan.

Armin is rather short for his age with a generally small frame, although years of military training have given him a somewhat muscular build. He has a rounded feminine face with blond hair that is cut in the style of a bob. He also has large, expressive blue eyes, brown eyebrows, and a slightly upturned nose that is often slightly red.[7]

During his childhood, Armin wore a long-sleeved single-buttoned jacket with a collared shirt, long dress-pants, and dress shoes.[8] As a member of the 104th Cadet Corps, Armin wears the standard 104th Cadet Corps uniform with a white button-up shirt underneath.

Armin is part of the Scout Regiment and dresses in their standard uniform. Underneath his short brown jacket, he wears a white collared button-up shirt, similar to the one he wore as an adolescent. Like his fellow soldiers, Armin has supplemented his attire with a large green cape when participating in expeditions outside the Walls.[9] He also has long brown boots that reach almost to his knees, as do the other soldiers.

In the year 854, he is noticeably a bit taller and has his hair cut shorter. As a soldier in the Scout Regiment, Armin is seen wearing their revamped black uniform for the night raid on Marley and a standard cloak for hiding purposes before he transformed.[10] Throughout the episodes, he wears a green military uniform and in the battle against Eren, and like both Mikasa and Jean, he wears a white long sleeved button-up shirt with a gray shoulder holster and black Survey Corp pants and boots.

In the year 857, his short blond hair sports fringes in each side.

Colossal Titan form

In his Colossal Titan form, Armin was entirely skinless and was extremely tall, roughly similar to Bertholdt's Colossal Titan. His Titan had elongated, stocky arms reaching its knees and very muscular legs with short thick feet. His Titan's feet were shaped so that it could stand without falling over due to its proportions and height. Armin's Titan's upper body was also fairly skinny, with an exposed rib cage on the front and sides. Its face was missing a nose and almost all of its skin, which was replaced by bare bone. The eyes of Armin's Titan form were sunken in and somber, with muscle surrounding them. Armin's teeth were shown due to the lack of skin on his cheeks. However, unlike the previous Colossal Titan, Armin's Titan had lips which were surrounded by some muscle. What made Armin's Titan particularly unique was the exposed windpipe that could be seen at its neck, with only two tendons in front of it. It also lacked visible outer ears.[10]

Even when he was young, the naturally curious Armin had a deep fascination with the world beyond the Walls.[8] As a child, he found and studied an illegal book about the outside world that was owned by his grandfather. He told Eren Jaeger, his best friend, about the book and the information that was inside it. Armin was branded a heretic by the other children, for his unusual interest in the outside world, and was frequently picked on.[8] Too timid to defend himself, Armin would often need to rely on his friends (Eren and Mikasa) to protect him from local bullies. This, coupled with his frail physique, was a source of much shame for Armin, leading him to have poor self-esteem and believe himself to be a burden upon others. Because of this, Armin has always been very eager to prove his worth. As a child, he hoped that one day he would be able to consider himself a true equal to his friends.[7]

Armin prepares to take action

Armin continued to have low self-esteem during his training years and for a short while after graduation. During this time Armin considered himself to be useless and a burden due to his lack of physical strength and physical skill. However, soon after graduation, he came to learn that his mind is an equally valuable asset to the military and that he is not useless or a burden as he can use his brain to help people.[11] Consequently, Armin gradually gains confidence in himself and his abilities. Nonetheless, he can still be hard on himself at times. The fact that he is so willing to sacrifice himself to achieve a goal shows that he still does not value his own life as much as he should.[11]

Armin is exceptionally loyal, brave and selfless. He constantly worries for the safety of his friends. Armin is always prepared to throw himself into dangerous situations to save them, even offering to sacrifice himself for Mikasa.[12] When he, Jean Kirschtein, and Reiner Braun had to decide who would be left behind without a horse, Armin immediately offered himself without hesitation. When Jean was injured in battle, Armin rushed to his aid, placing himself in danger as well.[13] Although he and Eren were determined to live their dream of seeing the outside world, Armin was content to give up his life in order to defeat the Colossal Titan and to have his dream fulfilled through Eren.[14] Armin is also very level-headed, keeping Eren and Mikasa under control when their emotions get the better of them. He has talked down a fight Eren started with a soldier and restrained Mikasa from acting rashly during Eren's military trial.[15][16]

Armin is a very analytical person. He likes to think deeply about situations and solve problems using his mind. These personality traits, in conjunction with his intelligence, good judgment, level-headedness, ability to plan ahead, and ability to come up with creative ideas and think outside the box, make him a great tactician. He is not an extrovert or loud person. When he was suddenly thrown into a leadership role that involved being in the spotlight, speaking in front of people and ordering people around constantly, he got quite anxious and momentarily froze up.[17]

Armin has shown great investment in humanity's future and is always striving for and thinking about how he can change things for the betterment of mankind.[11]