AruMika

AruMika is the het ship between Armin Arlert and Mikasa Ackerman from the Attack on Titan fandom.

Canon
Mikasa and Armin have been friends ever since before joining the 104th Cadet Corps and before that day. Armin would often get teased and bullied by older boys, Mikasa would usually defend Armin by beating the older boys which made them afraid of her when she would always come and aid Armin. Armin admired Mikasa's strength because of this and felt like he wasn't good enough, later Mikasa is responsible for Armin's character development which made him much more confident in himself.

In the Battle of Trost District, Armin is left a sole survivor as the rest of his team got eaten by Titans, this includes Eren as well. Mikasa finds Armin who begins to burst into tears informing Mikasa the deaths of his team and Eren, as regretful he is Mikasa comforts and informs Armin it wasn't the perfect time to get emotional so suddenly.

Fanon
The duo are more seen as a friendship rather than a romantic pairing due to Mikasa's crush on Eren.