Call of the Broken (and Eremin fanfiction)

Eren Jaeger hasn't seen his best friend Armin in almost seven years, not since Armin's parents took them with him outside the wall. Since then, Eren has grown up and joined the scout regiment and he is about to embark on their first mission with them to reclaim Wall Maria. However, during the journey he encounters something, or someone, he didn't think he'd ever see again.

(Disclaimer: any narrative changes made from the original source have been made to fit this fanfiction