Sakido telling Eric a little about her past in chapter 17. While she doesn't explain to Eric in detail, we (the readers) get to see how much she regrets how her life turned out, culminating in her 'hearing' Darius' voice in her head. Anyone who's read the comic will probably find this scene heartbreaking.
The climax of the fic has several. First is after Eric and Sakido get captured by the rebels, with Sakido being unable to do anything lest the rebels kill Eric, while Eric is forced to watch the rebels abuse Sakido, unable to do anything about it... at least until he enters an Unstoppable Rage. Second is after Sakido takes a bullet to the stomach. Its clear that she's dying from blood loss, and her apologizing to Eric while Eric tries to reassure her that everything is going to be alright, though its clear that he's also getting desparate. Fortunately, Broxis was nearby and had enough magic left to temporarily stop the bleeding, giving Eric the time to get Sakido to their camp and treat her wounds