Finished my re-watch of Eureka Seven via Netflix...I'd forgotten just how weird that show actually gets near the end. It was emotionally satisfying and not quite the bummer I'd vaguely remembered it to be. The ending is actually ambiguous and leaves room for hope.
**SPOILERS FOLLOW**
I'm just now starting Eureka Seven AO and trying to figure out its relationship to the original series. It definitely seems to involve a time-travel twist *backwards* in time...such that the events are actually kind of a "prequel" to the events of Eureka Seven proper. However, there seem to be certain characters who "remember" the alternate future timeline; Near as I can tell so far, Eureka was pregnant with her and Renton's son when she was flung backwards in time to 2020s Okinawa, which in this timeline recently declared independence from Japan. Eureka gave birth to her son Ao on the island of Okinawa. Her appearance on Okinawa was regarded by many as a bad omen; she seems to have disappeared some time not long before Ao reached his teen years, however, leaving Ao in the care of an senior Okinawan physician who took them both in. Ao has the eyes of a Coralian but his hair is ordinary brown at first. He has a crush on an Okinawan local girl named Naru. Lots of action happens and the end result is Ao finds himself in control of an early type FLO (KLF?) that loosely resembles Nirvash. And for whatever reason, he now has the teal blue hair of his mother and looks more fully like a human-form Coralian. It's....interesting and visually compelling, but also a little weird. No information whatsoever about Renton's fate; though at this point I'm assuming he's dead or had to ditch his physical body the way his father Adroc did before him. Like father like son, Ao has "daddy issues" the same as Renton--both have the indignity of heroic but absentee fathers.
I remember saying once that the Eureka Seven movie ends happier than the series does...but that's arguable as well...yes, both Eureka and Renton are still physically alive at the end of the movie, still on the planet...but Eureka's mind has been wiped and she's basically a blank slate who will have to re-learn everything...I guess I'd assumed (probably incorrectly) that they both died at the end of the original series, but I no longer think that's true, given the canonicity of Eureka Seven AO.
I was also emotionally satisfied to see Anemone & Dominic hook up at the end of Eureka Seven (original series). They re-appear in the Eureka Seven movie as mature adults & life partners.
Stephanie Sheh does appear in the credits of Eureka Seven AO as Eureka, though she mainly appears in flashbacks in Ao's memory at first, with few spoken lines. Ao's memories are unreliable, or history is more complex than we think. Eureka is shown in Ao's memories with her teal blue hair, but in photographs she has brown hair (but Coralian eyes). Perhaps she dyed her hair to better assimilate on Okinawa.
The humans of 2020 are aware of the Scub corals...the Corals themselves are a curiosity, but the real threat comes in the form of so-called "Secrets" or "G-monsters" that are giant alien spacecraft that are openly hostile and impervious to conventional Earth weapons. They can only be destroyed by mecha like Nirvash and its variants.
We learn by Episode 6 (where I left off so far) that the "Mark I" is indeed somehow TypeZero Nirvash...it remembers Eureka, and it identifies Ao as her son through bio-markers and accepts commands from him as well. No doubt there are also bio-markers from Renton, since Ao would have half of Renton's DNA besides Eureka's, and the two together allowed Nirvash to operate at maximal capacity. Ao ought to be half Coralian, half Human. It remains to be seen how this will play out in the series.
I've seen this series trashed by other Anime fans but from what I've viewed of Ep.1-5, I've enjoyed so far. I'm not prepared to abandon this ship just quite yet.