EreMika

EreMika is the Het ship between Mikasa Ackerman and Eren Jaeger from the Attack on Titan series.

Canon
Eren and Mikasa were 9 years old when they met for the first time. Eren's dad was scheduled to visit the Ackerman house as a doctors appointment and brought Eren along in the hopes of the two would become friends. They arrived at the house only to find the girl's parents dead bodies on the floor, her father having been stabbed in the stomach while her mother suffered a deep cut from an axe. Mikasa was missing from the house, having unfortunately been kidnapped by her parent's murderers, a group of human traffickers who intended to sell her as a sex slave.

Eren arrived in time, despite his father's orders not to pursue them, and tried to save her from the kidnappers, killing two in the process using a knife. But the third one managed to grab Eren and almost strangled him. Eren screamed Mikasa to fight and his words made her awaken a superhuman strength, which helped her to kill the man and save her new friend. Later, Eren offered her to come home with them after giving her his red scarf.

This scarf has since become a huge symbol in their relationship.

Mikasa has grown protective of him, often saving both him and Armin from bullies. This fact annoys Eren a lot, who envies her strength and has seen her as an overprotective mother in the past.

Mikasa will do anything in order to keep Eren safe and at her side. Even if it's in a life or death scenario, one such example being chapter 50 of the manga, or its counterpart season two episode twelve from the anime.

Fanon
As of May 2018, Eremika as a ship often comes into conflict with other ships. Primary examples include Eremin and Ereri, which are often topics of debate in forums and videos. As far as canon is concerned, Eremika and Eremin are often seen as displaying the majority of on-screen canon. Both ships involving fairly large fanbases, Eremika being the most popular in Japan. Though Ereri currently has the larger fanbase in the United States.

A certain theory that has evolved from Mikasa's scarf being changed from grey to red for the anime and live action. Fans speculate that this could be a reference to the red string of fate, a piece of Japanese folklore often described as a force that connects soulmates or lovers. This is still widely debated but is still a very popular fan theory.

At the time of this articles writing, Eremika currently has 539 stories listing the Eremika pairing on https://www.fanfiction.net/. For comparison, Ereri currently has just over 2,300 stories with the pairing listed and Eremin has 145 fanfics.

Fandom
AO3