The stupidity of teen pregnancy in addition to avoiding a fate equal to death. There was nothing worse than having a child that was just a means to an end, not because of personal relationships between two people.

I wonder how come btw we dont see the wall titans turn back into human and the tentacle creature die after eren is killed, I wonder if the author ever said why.

I have two theories about the Wall Titans.

1. The first theory is that they did turn human and we just didn't see it.

2. The Power of the Titans disappeared, but because these Titans were transformed for so long, they didn't have an original body to return to, so they perished along with the Power of the Titans.

As for the Shining Centipede, it didn't die. We're hinted this much. When Eren was killed, the creature went away, but it didn't die, because after they bury Eren under the Tree on Paradis Island, generations later, the tree has transformed into a Titan tree the same as the one where Ymir found the creature in the first place, meaning that the Shining Centipede isn't dead and merely waiting for that child in the post-apocalyptic world to find it and become the NEW Founding Titan.

Cool theories

Is the centipede thing a theory or was that confirmed in the manga or somewhere else?

The centipede, rather the source of all living matter, was featured in the Ymir's memories and during the Battle of Heaven and Earth. So no, not a theory.

Considering that the tree Eren was buried under on Paradis became a Titan tree, and it's more than likely that the author intended for us to link it to the Founding Titan.

One problem with the Wall Titan theory: Ymir had been a Titan for over sixty years before she regained human form. If all that’s left of a Subject of Ymir is their spine and brain when they transform initially, returning to human form upon consuming someone with the power of the Titans, the same should apply when the Founding Titan is exploited, only without the thirteen-year limitation.

Unless they were never Subjects of Ymir at all, but just extensions of the Founder.

Well, the difference here was that Ymir was granted power by the Founder which allowed her to take human form again (Via the Jaw Titan). The Wall Titans were not. It is the exact opposite actually.

Ymir lost her Pure Titan form because she gained Titan Powers.

The Wall Titans lost their Pure Titan form because Titan Powers ceased to exist.

I think Eren shouldn't have died, but should have rather ran away with mikasa like the scene which was shown right before he died. Eren sacrificed the world for mikasa, and mikasa sacrificed eren for the world. Eren couldn't run away because that's not part of his personality and he ain't a coward, but rather a hero who never surrenders and have always cared for his friends and family.

That was a good idea, but the episode insinuates that the rumbling happens anyway regardless, but this time it's Marley causing the ruumbling, and everyone, including Eren's friends would die. So if Eren didn't do it, then Marley would have, and instead of everyone dying by Eren's hand except for the Eldians, the Eldians would have ALSO died. Or at least, that's what I took from it. Not to mention that it was Mikasa's decision to kill Eren that ended the power of the Titans and the cycle of which would have continued had she married him.