Bro I'm trying to remember this Eremika story and I'm asking you because I think you commented. (Cuz you everywhere lamo)
Eren and Mikasa were rivals in this story. The first two chapters were "Hi, I Eren" and "Hi I'm Mikasa" The story also liked to include a group chat where the main cast of Aot would talk and Eren and Mikasa would bicker. There was also an incident where Eren crashed a golf cart, a chapter called "4th of July" where Eren punched Jean, one where Mikasa was really drunk, a beginning of summer bonfire, a movie night at ymir's house, and finally, one where Eren and Mika dyed their hair purple with bleach.
Hope I didn't try to remember this all for nothing, but don't worry if you can't remember the fanfic, and I'm still not sure if you even read it, but thx! Also sorry for any grammatical errors, I'm too lazy to read this over lol. :)