Armin Arlert

"People who can't throw something important away can never hope to change anything."

- Armin Arlert

Armin Arlert is a childhood friend of Eren and Mikasa’s best friend the deuteragonist in the series. Although physically and emotionally weak and hates having to rely of Eren and Mikasa, his strategic abilities and intelligence have saved Eren and Mikasa multiple times. He is instrumental in discovering the identities of the Titan infiltrators, and becomes one of the Survey Corps' most vital members.

Personality
Armin was very timid as a child and coupled with the fact that he was physically frail, often ended up an easy target for bullies. He was so timid that he would refuse to fight back despite being taunted to do so, always requiring Eren and Mikasa to fend for him. As such, he grew up having very low opinion of himself and thinking that he is useless. His enlisted only because his two best friends were enlisting. Despite being timid, he has a variety of traits that contrast his timid self, which began to show as he grows older and learns to appreciate his own talents and develop a higher opinion of himself. He has a big dream of wanting to venture outside the wall to see the world - a dream that he shares with Eren; he is also a loyal person who is willing to put himself in harm's way to defend a friend, shown when he was, along with Mikasa, willing to defend Eren against hostile fellow soldiers despite the very high risk of being killed; and during training, despite always on the verge of failure due to his physical frailty, he was shown to be very persistent despite the odds, refusing to give up and did his best to catch up with his friends. He was also shown during training that he has a sense of dignity when Reiner offered to carry his gear for him during a march, he refused the offer outright due to the fact that doing so would meant that he is cheating. He is the brain power of the team as he impressed Dot Pixis, the high ranking officer in charge of the cities defense, by his brilliant plan to attract titans during the battle of Trost.

Before Year 845
Armin originally lived in Shinganshina with his parents and grandfather. He was a close friend to Eren and used to discuss with him about the outside world with it's salty oceans, deserts and other surreal places. He inspired him to dream about being free and explore the world beyond the Walls. He used to get into trouble with local bullies for talking about the outside world and was regarded as a heretic.

Year 845
During the attack on Shinganshina, he asks Hannes to fetch Mikasa and Eren as they were going too close towards the Titans. He and his grandfather sit aboard a ship, waiting for Eren and Mikasa.

Year 846
His grandfather left with other refugees on a campaign to retake Wall Maria. However, he died on the mission and Armin was left alone with Mikasa and Eren.

Story
Armin decides to join military training along with Mikasa and Eren, because after his parents and grandfather got killed, he couldn't sit around doing nothing. He was able to pass the basic aptitude test after some effort and tries to help Eren with it. Armin was considered weak in physical strength and graduated below the top ten. However, he was top of the class when it came to theoretical courses. Although his plans have saved Eren and Mikasa several times, he doesn't realize it and despises himself for being reliant on them.

Armin fears humanity's fate when he hears of the attack on Trost. He trembles in fear and was having problems in fixing his gear, when Eren tells him that not all was lost. Armin joins Eren's squad to guard the middle of Trost and departs with him to their prescribed location. On the way, Titans attack and eat up everyone in his squad except him. Armin supportively blamed himself for allowing Eren to sacrifice himself to the bearded Titan. Mikasa tells Armin that his strategies have always saved their lives and he should have more faith in himself.

In Trost's military headquarters, a number of Titans were attacking them and had took control of the supply depot. Armin devised a plan, wherein the soldiers would lower themselves via an elevator and lure the seven Titans towards them. As soon as they get close enough, everyone would shoot their eyes with firearms, momentarily blinding them and seven skilled soldiers, who would be hiding beforehand, would attack and kill those Titans from behind. The plan succeeded and everyone was able to refill their gas tanks to return alive.

After recovering Eren, he was detained by a group of soldiers and was going to be executed. Armin and Mikasa defend him, as he wakes up and is surprised. Eren plans to escape over the walls unless Armin was able to convince the soldiers regarding Eren's value to humanity. Eren tells him that his quick thinking had saved him and Mikasa before, as he was the one who went to Hannes when Shinganshina was being attacked. Armin, more confident than ever, walks over and tries convincing the soldiers about Eren's strategic and tactical importance in turning the tide of the battle in Trost. As a soldier, he passionately decides to die for this cause and makes a grand salute. Pixis notices his determination and passion and prevents their execution.

Now with a boost in self-confidence, he tells the senior strategists about a plan to retake Trost. He tells them that Eren could carry the boulder over to the hole while other soldiers could lure the Titans towards the walls. They proceed with the plan. Later, when Eren lost control and was knocked out, Armin goes running towards Eren and lands on his back. He remembers the position from where Eren had risen earlier, so stabs him a little askew so that it wouldn't be fatal, but would wake him up. He reminds Eren of his dream to go outside and his personal vendetta against the Titans. Eren, successfully motivated by Armin's effort, carries the boulder and plugs the breach.

After the two Titans, Sonny and Bean, were slain, Armin notices Annie in possession of Marco's Three Dimensional Maneuver Gear. He realizes that Annie might have been the one who killed the two Titans but decided not to believe his train of thoughts. After joining the Scouting Legion with Eren, Mikasa and the other graduates (excluding Annie Leonhardt), they went outside Wall Rose for the Scouting Legion's 57th expedition, when they were confronted by the sudden appearance of the Female Titan, seemingly knowlegeable about military formation. She attacked Armin while he was wearing his hood, under the impression that he was Eren. However, once it was removed, she realized she had the wrong subject and left him aside. Armin noticed a few things regarding the female Titan : she avoided killing Jean and him even though she had the chance, and it seemed as though Reiner had carved letters onto her palms, after which she directly charged towards the rear of the middle flank. Adding the knowledge that Annie had used Marco's gear during the checkup, Armin realized Annie was, indeed, the Female Titan.

Armin asks Annie for her help in hiding Eren because she was in the military police and they needed her to let them pass through Wall Shina without suspicion. Annie accepts and Armin explained that he wanted to take advantage of the geography there rather than use the 3DMG to bust through. As she was leading them to a hiding place, Annie refused to go inside to help them escape and asked him why he was looking at her with suspicion. Armin then took the time to ask her the reason she was in possession of Marco Bodt's 3DMG. He recognised it not too long ago because he and Marco would often do routine check-ups to make sure they were in pristine shape. Annie confessed that she found it after Marco died and that she used her own 3DMG to kill the two captured titans. She then asked him if he had already come to all those conclusions, why hadn't he taken action earlier. Armin reasoned that he didn't do so because he wished to believe that there was still something wrong with his train of thoughts. It was when Annie refused to kill him that things turned out the way they did.

Armin attempts to capture Annie by firing the signal from his flare gun letting the townspeople capture her. As the people tried to restrain her, she managed to injure herself with a sharp metal projection hidden in her father's ring. Noticing this, Mikasa grabs both Eren and Armin and takes them further underground as Annie in her titan form attempts to capture them. When Armin learns his plan had failed he attempted to start plan B, trying to encourage Eren to fight Annie. Eren tried to transform into his titan form, but he was unable to do it. It was only then Mikasa and Armin learned why, he was reluctant to fight Annie again because he still couldn't believe that Annie was indeed their enemy. And he didn't want to fight against one of his comrades. Having no other option, Armin tells Eren that he and Mikasa would go out through each of the two openings. Annie would go after one of them and Eren should utilize the opportunity to escape via the other opening. Realizing that his friends were in danger, Eren finally transforms into a Titan and fights Annie.

After Annie's capture, Armin tells Jean Kirschtein that Eren's summoning to the King were cancelled and that Annie is the Female Titan. She's been detained underground after encasing herself in a crystal to avoid interrogation. Armin couldn't understand how the walls were built in the first place because there were no stones or bricks around. He hypothesizes that the titan's hardening capabilities were employed to build the walls. He believes it could explain how Annie was able to encase herself in a crystal. Armin's hypothesis was confirmed when the rock sample Lt. Hanji had picked up from Annie's body matched the crystal properties of the Walls. He and the others learn from Lt. Hanji that the only way they could repair the walls is if Eren can use his hardening abilities to help fix Wall Rose. Pastor Nick tells them about a girl in the Scouting Legion knowing more about what's going on and it's up to her to decide if she'll talk. Armin then recognized Christa because she was often seen with Ymir.

Once the Scouting Legion had rescued the others from the South Squad, Armin learns that Christa's real name is Historia and how heavily injured Ymir was during her fight with the titans. He immediately learns of Reiner and Berthold's secret correspondence with Annie. Like Mikasa, Armin was very angry to learn about their betrayal after overhearing the confession about them being responsible for Wall Maria being breached.

During the battle with Bertholdt and Reiner, Armin states that the Colossal has very slow movements and that they should exploit it. However, they were taken by surprise when he uses his vapors of heat to keep them off him. Realising that Berthold is just as desperate to stay alive, Lt. Hanji orders Armin and the other members of the Scouting Legion to go after Reiner. Armin discovers a weak link to Reiner's line of defense when he saw his armor break. Giving Mikasa and extra set of blades, he tells her to go ofter the back of his knee caps. Soon Berthold took everyone by suprise by falling off the wall.

With Eren and Ymir now kidnapped by Bertholdt and Reiner, he focuses his attention in helping Mikasa and the others until help arrives. Armin tells her the news that she had been dreading and wrapping her lower face in the scarf, she cried. She asks him why he always has to leave them behind when trouble rises. As Armin tries to console her, Hannes arrives to give out rations to everyone in the Scouting Legion. He tells them that Eren has always been like that, running into fights despite knowing the odd are against him. Hannes even mentions that although he won't admit it, he always knew Armin and Mikasa were there to help him out. Reinvigorated and determined to rescue both Eren and Ymir, he takes his stance with the Scouting Legion, Wall Guards and Military Police. Armin wants Historia to stay within the walls, but she refuses and decides to join them.

Armin and the others reach the Forest of Giant Trees where Reiner and Bertholdt were resting. While inside the forest on their 3D gears, they notice Ymir's Titan form. Armin suspiciously notices that she was surveying everyone and wasn't responding to anyone. Her suspicions were confirmed when she captures Christa and escapes. He realizes that Ymir was definitely working against them.

Abilities
Being one of the physically weakest soldiers there are, he is rarely assigned to the frontlines and rarely seen using his 3DMG for fights. His main strength however, lies within his intelligence - an innate abilities in deduction and forming strategies, be it in a war room or on the fly, as well as an eye for obscure details, making him a remarkable field tactician, a trait that only he displays among the current recruits. His strategies helped save his fellow soldiers numerous times and more remarkably, he is the key person who deduced the identities of all hostile titan shifters among the current recruits. He wasn't able to display his remarkable intelligence earlier due to a serious lack of confidence in himself. After acknowledging that he is actually far more useful than he thought he is, his genius as a tactician began to show and thus far, even commanders are shown to take his opinions in matters relating to titans seriously.

Trivia

 * The name "Armin" may have multiple meanings, either from an old German word meaning "whole", or "Herman", meaning "soldier".