This episode gives us a little more insight into the nine Titans. The goals of Eren Krugar and the eventual goals of Grisha Jeager, as well as a little more information into the subjects of Ymir.

The most important and most depressing thing we learn this episode is the unfortunate truth of what happens to people who inherit one of the nine Titans. The unfortunate truth that they only have thirteen years to live after taking it on, which for Armin means another thirteen years and for Eren. Roughly eight years left or so, this thirteen year limit is why the Owl needed someone to inherit his Titan and he chose Grisha. All the way back when he was a child, he chose him because of his hate.
He tells him to go inside the wall and capture back the founding Titan. Only then, only then could Eldia rise back up against the Marley’s.

Well, we know that Grisha is successful in this.

So now Eren is in possession of two of the Titans. The founding Titan, and his main Titan form that he inherited from the previous Eren. The Titan known as the ‘Attack Titan’. Mikasa and Eren are let free from their imprisonment early and brought before the queen and the generals to make a report on everything they found in the basement and to start making a plan on where to go in the future. As they are speaking about everything they found and everything that has happened, Eren realizes something about the last time he used the power of the founding Titan.
He stands up in the middle of the meeting and screams.
He brushes this under the table and Hange sort of brushes it off too as him going through a ‘phase’ and they all agree that he is ‘about that age.’ but it’s more that he connected the fact that the last time he used the power of the founding Titan.
He was touching the smiling Titan, in other words, Dina’s Titan. A titan of someone of royal blood.

Rightfully, his immediate fear is what the military will do to Historia if he reveals this information. So while it’s immensely important, I can’t really blame him for keeping it to himself.

The other most important thing we find out about is the connection between all subjects of Ymir.
The flow of memories and emotions in a circuit that connect them all, I feel like we see it for a moment when we see Historia reading a letter from the modern day Ymir. She gets flashes of something, memories perhaps, from touching the letter and we see it again on a grander scale.
Memories moving through time, as Eren Krugar speaks to Grisha. Right before he injects him with the Titan serum and passes on his Titan, when he tells Grisha to find someone he loves beyond the wall and also begs him to help protect Mikasa and Armin.
Grisha questions who those people are and Krugar doesn’t know. All he can do is blink and right as the credits begin to roll he asks

“Who’s memories are those?”

It’s kind of chilling actually, to think that we could be connected to the future and the past.

My goodness, I loved this episode. I’ve loved these last few episodes, it’s really changed the tone of this series. The Titans were our enemy, and it was bad enough when we thought they were our only enemy. However, the true enemy of the people living behind the wall.
The true enemy of the subjects of Ymir, is humanity itself. It will be interesting to see how this series proceeds from here.