Primitive Desire

Primordial Desire is the first chapter of the fourth volume and the fourteenth chapter overall.

Summary
As the soldiers fight the onslaught of titans drawn to Eren, Armin tries to bring Eren to his senses, reminding him of his desire to see the outside world. Slowly and in the nick of time, Armin is able to bring Eren around. He regenerates and heaves the stone onto his shoulders, carrying it towards the hole, much to Mikasa and the rest of the escorts surprise. With the mission now on its way to success, the soldiers have a new found energy and vow to protect him even if it costs them their lives

In an attempt to get the titans attention off of Eren, a small group approaches them on foot. The plan works, but puts them at a disadvantage when they need to escape. Ian orders his team to follow the others so they can hand the target over to them. Eren's body feels like it's being crushed under the weight of the boulder. He sees Mikasa and Armin and worries that they will fall prey to the titans. As Eren struggles with the stone and moves toward the hole, the soldiers are barely able to keep away from the titans. As one manages to get right in front of Armin and Mikasa, another soldier uses his 3D Maneuver Gear and stabs it in the eye, allowing Mikasa time to get behind it and kill it. Armin looks over his shoulder and sees Eren is only a short distance away from the hole now. Eren plugs the hole, but at a great cost. Riko remarks that everyone has dies as a result as she fires the yellow flare, marking success.

Back atop the wall, Pixis, seeing the flare, orders for reinforcements to immediately be dispatched. With the titans moving towards them, Riko orders Mikasa to climb up the wall. She replies that she'll only withdraw after Eren is retrieved. Armin, now at the back of Eren's neck, tries to pull him free from the flesh of his titan form. Mikasa asks about his condition. Armin informs her of his high fever and one part of his body still being stuck. Riko suggests cutting the limb off, but Armin is able to pull him free before she does. As he pulls, they both fall to the ground, nearly at the feet of two titans. Mikasa rushes to their side, but she won't make it in time. Out of nowhere, a soldier swoops in and dispatches of both titans. When the bodies fall, Eren manages to open his eyes and sees the emblem of the Scouting Legion; it's Rivaille. With the success of the mission, the Scouting Legion and the Stationary Troops's Engineering Department hurried in and did their part. Wall Rose is sealed and protecting everyone from the titans again. They delight in humanities first victory against the titans, but acknowledge that it came with a high cost.