Levi Ackerman has been told he has PTSD, Erwin Smith has become worried over the man who's so close to a point of loosing all sanity. The two have a forbidden secret they must not tell anyone, being in a unofficial relationship would ruin both of them. Though, they can't keep away... Levi's sanity might just shatter, and all hell will come if the demon of the underground breaks free from his chains.
Eren has always had feelings for Levi, but Levi has always been taken by Erwin... Though, when Levi gets sick, Eren has a chance for new love.