After some sidetracks, this episode brings the focus back to the scout regiment. It turns out that they've been running experiments that have yielded positive results. Eren is getting a better handle on his titan abilities. Said abilities have allowed the city to bolster its defenses so that they can kill titans without having to endanger human troops.
This brings the fact that titans are transformed humans into focus as Eren starts to wonder just who they're fighting and why they're doing what they're doing. The discussion triggers a flashback of sorts for Eren, who suddenly remembers a man who may or may not have known his father. As it turns out, that man is Eren's former drill sergeant, Keith Shadis.
It's a bit of a contrived coincidence, then again, it is a fairly small-town like setting, so I suppose it's not outside the realm of possibility. It still seems rushed and forced, though there are some positive aspects to the development.
A lot of the episode is a flashback, as Shadis tells Eren how he came to know Eren's father and the impact that the association had.
We see that Shadis first came across Eren's father, named Grisha, after finding him outside the walls. Grisha had no real memory of who he was, but he did know that he was a doctor and offered to work in that capacity. I'm guessing that memory loss is a result of the Reiss', but we'll see if they elaborate on that at all later.
It turns out that Grisha is a very skilled doctor and he becomes something of a town hero. In the wake of this, Shadis becomes convinced that he too is special. He is soon disavowed of this notion and takes the opposite mindset, that he is nothing but a bystander (title drop!)
This episode had some good character elements. It was kind of a surprise to see such a minor character make a return and we are getting new information about Eren's father. Still, this episode didn't move things all that much and I was a little thrown when the credits just started rolling when they did. I wouldn't be surprised if the information shown here comes back in bigger ways later on down the line, but I don't know if this will go down as one of the season's more memorable episodes.