Eren doesn't remember how he died.

All he remembers is falling to sleep after his 45th birthday, closing his eyes to listen to the sound of the ocean, and then waking up being a tiny human baby listening to his mother, who is now somehow alive, cooing at him while he cries now tears of joy, because he forgot why he originally woke up screaming.

Eren thought about it for awhile but gave up after a few hours, just supposing that he died in his sleep, even though it nagged at his mind.

Eren then began thinking about his family, and even though it consists of mostly the same people, it was very odd.

His dad was still named Grisha and still a doctor, but he didn't travel as often as he had in his previous life, and his mother who he thanked the gods was even alive, was still his mother. The rest of his new found reality was odd though.

His mother wasn't a regular stay-at-home mom anymore, she was something in this world called a "mayor"? There was much to learn from this new world.

His fathers-father was the Ape titan, this scared Eren the first few times he saw the man, he tried biting him a few times, until the man had told Eren that he wasn't a bad man in this new world, and that titans don't exist. Eren thinks the man new about his memories but he didn't dwell on it to much. 

Eren also had new siblings that weren't either Mikasa or Armin. Eren was actually not all that surprised after finding the Ape titan as his grandfather.

Bertolt the Colossal titan and Ymir the Dancing titan, were Eren's new siblings.

And for some reason his "cousin"? was living with them due to some kinda family issue that Eren didn't understand even after listening to the 'adults' conversate  about it.  Eren couldn't understand why a trip in the sky was more important than looking after your own child, even though he personally loved the feeling because of the 3DMG, he wouldn't abandon his own just to fly away. ;-;

His cousins name was Isabel, and even though they couldn't talk correctly, cause the tongues they had were to big for there mouths and Eren had to stop himself from wondering if that was true foe every baby, Isabel reminded Eren of a cross between Hanji and himself.

She had redish hair and vibrant green eyes, and she followed Eren around whenever they were allowed to crawl around out of that prison the adults called a play pen. It kinda reminded Eren of the walls and he always tried to scale it before his mom stopped him, he thought he could take the fall it wasn't that high up.

Another thing that was different about his new environment was that Erens house was REALLY big, not as big as Survey Corp. HQ's castle, but it could fit 4 little houses inside.