|I don't know what he is either...but we have to give our lives for him...with as much bravery as we can muster!|
|— Ian places his faith in Eren|
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.
Ian was also very brave man, caring about his fellow soldiers, as he us shown to save one of his subordinates from a Titan and is himself devoured in the process.
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. Mikasa is able to catch the Titan and slay it before it kills anyone, and Ian commends her for her efforts. He is impressed by Mikasa's professionalism, as she apologizes for damaging her blades during attack, though he is unnerved by her utter calmness in the face of a life and death situation. The team continues fighting off Titans until they receive the signal to evacuate. Ian orders his team to climb the wall and provide cover for the advance team as they also withdraw, but Mikasa disobeys his orders and leaves, despite his protests.
After a rampaging Titan is revealed to be a trainee, Ian is among the Garrison soldiers who surround him and his allies as Kitz Weilman questions the trainee about the nature of his Titan transformation. Mikasa is one of the two soldiers who take Eren's side, and Ian vouches for her skill, explaining to Kitz that losing her would be a great loss to human forces. Kitz ignores Ian's advice and tries to execute Eren and his comrades, but he is stopped by the interference of commander Dot Pixis.
A plan for Eren to use his Titan powers to seal the breach with a boulder is formed, and Ian is placed in charge of the Alpha Squad assigned to protect Eren on his mission. The operation goes sour immediately, with Eren losing control of his Titan form and attacking Mikasa before eventually collapsing. As Titans begin approaching, Rico Brzenska and Mitabi Jarnach advise Ian to abort the mission and retreat. However, Ian orders them to take their teams and protect Eren until he can recover. Rico tries to argue that enough soldiers have already died for Eren's sake, and Ian loses his temper, demanding that Rico tell him any other way to take back Trost without Eren. Rico is unable to give an answer, and she and Mitabi are forced to go along with Ian's plan.
As the soldiers fight, they are gradually overwhelmed as more Titans continue to pour into Trost. As Ian is about to order a retreat, Eren finally awakens and begins to carry the boulder to place in front of Trost's gate. Ian orders his team to protect Eren at any cost, and orders Mikasa and Armin Arlert to stay near Eren to defend him. He then notices that Mitabi's team, with no buildings to utilize their gear, are approaching the Titans on foot to get their attention away from Eren. Realizing that there is no other way, Ian orders his team to do the same. Ian uses himself as bait to lure Titans away from Eren, and sacrifices his life in order to ensure the success of the mission. He dies after a Titan pushes him into its mouth in such a way that his head is bitten off by it.
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.
He was a highly capable soldier, and his leadership skills were trusted enough to earn him command of the Trost mission.
Ian Dietrich's statistics as of year 850:
- Ian ranked twenty-eighth in the Second Character Popularity Poll.
- He trained in Rico Brzenska and Mitabi Jarnach's same Training Corps class.