No, Eren isn’t the father. In both the manga and the official guidebook, it’s confirmed that Historia’s child was fathered by an unnamed farmer from her childhood village—someone who once bullied her but later felt guilty about it and ended up working at the orphanage she ran. Their relationship was never portrayed as romantic in the series; the pregnancy was a deliberate choice Historia made to buy time and avoid being forced to inherit the Beast Titan from Zeke right away. The anime doesn’t spell this out as explicitly as the manga does, which is why the theory took off for a lot of viewers. The private conversation between Eren and Historia, the timing of the pregnancy, and some vague framing around the final panel all fueled speculation, but nothing in the actual story shows a romantic or sexual relationship between them. Eren respected Historia and confided in her about his plans, but the canon answer is the farmer—she even marries him afterward.

The show never addresses the Underground City’s fate because the narrative treats it as a background detail of Paradis’ internal hierarchy rather than a factor in the global-scale events of the Rumbling. Located deep beneath Mitras inside Wall Sina, it housed a large population of the island’s poorest and most marginalized residents, including people like Levi before he left. When Eren unhardened the Walls, the Colossal Titans embedded in them broke free and began marching outward; this process itself would have shattered the surface above the cavern and generated catastrophic seismic shockwaves through the surrounding rock. The artificial lighting, multi-story buildings, and support structures visible in depictions of the city would have been highly vulnerable to collapse under that level of continuous vibration, and the tunnels connecting it to the surface would almost certainly have been sealed or destroyed in the initial chaos. In practical terms, most of the population likely died quickly from structural failure, falling debris, or being trapped with limited supplies once the capital above was thrown into disorder. The few who might have reached the surface would have blended into the broader refugee and survivor population already dealing with the loss of the Walls and the departure of the Titans. The story’s focus stays on Eren, the Alliance, and the external destruction of the Rumbling, so the Underground simply falls outside the frame—much like many other secondary populations on Paradis who are never shown in detail once the Walls come down. Its omission is less a deliberate mystery than a consequence of the series prioritizing the ideological and large-scale consequences of Eren’s plan over exhaustive accounting of every community on the island.