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 needing Eren Yeager and Mikasa Ackerman to fend for him. As such, he grew up having very low opinion of himself, thinking that he was useless. He enlisted only because his two best friends, Eren and Mikasa, were enlisting. Despite being timid, he has a variety of traits and talents that contrasts to his timid self, which began showing as he grew older and learnt to appreciate his own talents and develop a higher opinion of himself. He has a big dream of wanting to venture outside the walls 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. 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 to have a sense of dignity when Reiner offered to carry his gear for him during a drill and he refused the offer outright due to the fact that doing so would mean that he was weak and uncapable. He is the brains of the team and he impressed Dot Pixis, the high ranking officer in charge of the cities defense, by his brilliant plan to attract the Titans during the battle of Trost.



Garrison:
http://www.planetminecraft.com/skin/hannes-original-captain-of-the-garrison-force/




Survey Corps:
http://www.planetminecraft.com/skin/attack-on-titan--eren-jaeger-member-of-the-survey-corps/



Military Police: