EreMin

Eremin is the slash ship between Eren Jaeger and Armin Arlert from the Attack on Titan fandom.

Canon
Eren and Armin met each other as young kids in Shiganshina. One day after an encounter with bullies, Armin is approached by Eren who is curious as to why he did not defend himself, and whether he is tired of always losing. Armin replies that he has not lost since he did not run away, to which Eren asks his name.

The two of them soon become best friends, obsessed with what lies beyond the walls and inspired by each other to see for themselves. Both being outcasts, the two only really had each other before Mikasa came along. Eren, along with Mikasa, often defended Armin from bullies.

Eren and Armin both enlist in the 104th cadet training corps at the age of 12. On their first mission against the titans three years later, Eren saves Armin from getting eaten by pulling him out a titan's mouth and taking his place. Armin screams and falls to his knees when this happens, and later breaks down whilst breaking the news to Mikasa. To Armin's shock, Eren survives using his titan shifter abilities. Upon seeing Eren alive Armin becomes emotional and holds his hand.

After being captured by the Garrison, Eren transforms once again to shield Armin and Mikasa from cannon fire. He then puts all his faith in Armin to convince the soldiers to spare their lives - and it works. Soon after, Eren attempts to block the hole in the wall using his titan form, as proposed by Armin. Shortly into the mission, Eren knocks himself unconscious. However, he is soon back up on his feet thanks to Armin's motivational words and, thus, manages to successfully plug up the wall. Armin tries to pull Eren out of his titan afterwards and holds Eren's arm over his shoulder.

On the Scouts' 57th expedition, Jean tells Armin that he has always found Armin creepy for his attachment to Eren, suggesting he thinks they are a bit too close to just be friends.

After Annie's transformation when Eren is lying injured under rubble, Armin motivates him to fight, yet again, by encouraging him to let go of his humanity.

Armin helps rescue Eren from Reiner and Bertolt by emotionally manipulating Bertolt into letting his guard down. After Eren is retrieved, the two of them, along with Mikasa and Jean, ride their horses together in silence while morning the loss of Hannes.

The evening before the Shiganshina mission, Eren, Armin and Mikasa sit outside and reminisce about their childhood. Armin excitedly reminds Eren of the sea and the other various wonders of the outside world, having him promise that they will go there one day, to which Eren smiles and agrees to. When Eren is shaking on their journey to Shiganshina, Armin reminds him of the time when Eren fearlessly rescued him, and Eren reveals that it was a memory of Armin talking about the outside world which had given him the courage to do so. Eren stops shaking and thanks Armin.

During the Battle of Shiganshina, Armin convinces Eren to go with his plan to beat the Colossal Titan, even though it means his own death. After capturing Bertolt, Eren looks at Armin's burnt body with a sad expression. When Armin starts to breathe again, Eren moves close to him and becomes tearful. At Levi's arrival on the scene, Eren urges him to let him save Armin with the titan serum. Levi's decision to save Erwin instead causes Eren to stand in his way. After being punched by Levi and restrained by Floch, Eren once again attempts to save Armin by telling Levi about Armin's worth as well as his dream of seeing the ocean. In the end, Armin gets saved and, upon waking up, he receives a big, teary hug from Eren.

A year later, they finally make it to the ocean. While Armin finds happiness in achieving his lifelong dream, Eren is upset because he knows that, beyond the ocean, their enemies are lying in waiting. Eren and Armin soon develop differing ideas on how to deal with the Marleyans. As shown in the shooting range scene, Eren wants to fight them while Armin is content with slowly earning their trust and making friends with them.

After his attack on Liberio, Eren is helped on board the Survey Corps' blimp by Armin. The latter's expression, however, is not very welcoming, as he does not agree with Eren's ruthless actions. When they return to Paradis Armin confides in Annie that he no longer understands Eren.

Fanon
Fans have noticed their close bond that they have maintained for years, such as joining the military and fighting alongside each other to reach their goals of seeing the ocean. Though it is still in question whether their friendship will last or progress into something more (or even less) they have strong feelings for each other in canon.