Ian Dietrich was a team leader and member of the Garrison stationed in Trost District. He led Trost's recapture mission.
Ian was a taller man, with a fairly muscular build and hazel eyes. He had straight, dark blond hair parted down the middle and tucked behind his ears, reaching the lower back of his neck. Ian had a notably slim face with defined cheek bones and light skin. He had only been seen wearing the Garrison uniform, pairing it with a tan shirt underneath.
Ian was usually strict and brief, but when in less-tense situations, would engage in conversation with the soldiers he worked with. He also had good faith in his allies and was obedient to his superiors. He would usually plan strategies with his comrades in a candid manner and was noted to have a good knowledge of alcohol by his Commander, Dot Pixis. This however did not stop him from shouting orders to soldiers in desperate situations and thinking logically. Even when faced with the negativity of Rico and Mitabi, he chose to continue the operation to retake Trost District the way he thought was best, rather than retreating.
Appearance: Ian was a taller man, with a fairly muscular build and hazel eyes. He had straight, dark blond hair parted down the middle and tucked behind his ears, reaching the lower back of his neck.
Personality: Ian was usually strict and brief, but when in less-tense situations, would engage in conversation with the soldiers he worked with. He also had good faith in his allies and was obedient to his superiors.
Ian Dietrich in the story: After Trost District is breached by the Colossus Titan Ian is seen ordering Mikasa Ackerman to support the rear guard. She protests that she will only slow them down but Ian retorts that he did not ask for her opinion and says that she should just obey her orders. During the evacuation Ian's team tries to intercept an abnormal Titan as it targets evacuating civilians.
How Ian Dietrich echoes later: After Ian's death, Armin remembers him and Pixis for having enough resolve to sacrifice something to ensure success. When Hange decides to oppose Eren's plan to destroy the world beyond the Walls, Ian is one of the soldiers Hange remembers when arguing that their fallen comrades would not support destroying the world.
Source: Attack on Titan Wiki, available under CC BY-SA 3.0.