それは違うよ！！！！！！
Did that salty, un-dank baka even read my beautifully worded statements? I DID consider Levi as the uke, and it would still not be plausible for them to have a million babies together even if Levi joined in on the birthing (Levi is 34, 79-34 is 45, 45 + 64 is 109, 1 million/109 is 9174.31192661, that's 25.1351011688 a day, 12.5675505844 a day for each, which is STILL impossible. Also I must amend my previous calculations- if Eren birthed a million babies during his lifetime, that would be 15625 babies a year, aka 42.8082191781 babies a day, aka STILL IMPOSSIBLE) and this is not taking into account the time needed for basic needs, such as eating, sleeping, and killing titans.
Brain children would cause MENTAL wear and tear. Brain children can even cause the deterioration of neurons, and in extreme cases, death; therefore, making brain babies would not be a plausible alternative to the traditional route.
Also, I doubt that Eren and Levi have the capacity or the time to create a million computer programs in their lifetimes.
Surely, there isn't an efficient adoption system in this post-apocalypse, titan-ridden alternate universe, and the accrued pets and adopted children would surely die of neglect, since Eren and Levi must spend their time killing titans/screaming/angsting/cleaning, of course. Also, are there even a million children LEFT to adopt? The walls encompassed a tiny population in the first place, and then there were the titans.
Lucifer died of pregnancy (#tumor). He is sorely missed. Rip.
Kids are brats, so it does not incite the doki-doki ing of kokoros. It implies even more screaming. Imagine how much screaming that would be. a million children + Eren = decibel levels strong as Erwin's eyebrows (rip), strong enough to induce permanent hearing loss.