Adding to my previous brain dumb, so brain dump 2.0.
As stated, I see her clearly Gaian. Simple if her would be Demonothan or Angelions why should she care about earth at all?
Then my brain got on and on and doing that even now. Morther Nature is a concept that could also be done with an Demonothan or Angelions version for their respective planets. Although I don't think that a Demonothan, Angelions or even a Human Mother Nature looks like a Demonothan, Angelions or Human.
So going to the point back of the war, where the Angelions cleans their planet and a many search hideaway on the Demonothan, what would the Angelions Mother Nature do? Couldn't she be one of the fugitive of that war?
So Angelions Mother Nature escaped to Demonothan world. So the Demonothan world have now two Mother Nature and the Angelions world is lacking her.
Then with the Demonothan ark into the "unkown", it would make form my point of view, a lot of sense to bring along a Mother Nature with her power and skill, if you want to settle on a new planet. So, as they Demonothan thought the same and as they already have two Mother Nature, they invented one (Angelions Mother Nature) to their ark, cause it is the logical choice. As the Demonothan Mother Nature to be on her home world, where she knows her home world inside out, while the Angelions Mother Nature is alien to the Demonothan as well as both Mother Nature are alien to Earth.
So, Demonothan world have their native Mother Nature, the Angelions Mother Nature is not on the Angelions wolrd anymore with all what that implies and that in my thoughs are slowly loss of flora and fauna. Some time after the Angelions Mother Nature fleed from their planet, the Angelions come to understanding, after initial being happy to have one "unpure" thing less on the planet, what that really meaned, in the very long term their planet would become barren.
Thus they seek to retrieve her and come after the Demonothan. As they can't simple go with the "Well, in our insane hunt of all unpure being, we made an error and drive our Mother Nature away, now we now better and know we need to have her, so can she
pretty please come back to us?", the go with their remove all unpure beings form the world or in this case know universe and only a hand few know the real reason for the excalation war.
Meanwhile the Demonothan have prepared the ark and after the war started rushed the start of it, as you've written. On board was a (one) Mother Nature, what alone is already a secret. That the Mother Nature on board of their ark is the Angelions one, was the top secret. But the somehow this top secret information have been leaked to the Angelions and they send their own ship after the ark, with a simple mission: Find, capture and retrieve the Angelions Mother Nature alive or die in the attempt and don't come back at all.
So the Demonthan ark crashed on earth, after their travel and battle with the Angelons ship. As in the beginning only a few on board knew about the Angelions Mother Natrure and with some casualities due their batlle and crash, the ones that knew this became even less.
The try to survive and integrated themself into the earth ecoystem, what was going good and have lead to some of the old advance civilization. Then the Angelions ship crashed also on earth, their goal still the same (find, capture and retrieve the Angelions Mother Nature alive), but with the lacking power and the new situation their where in it (Demonthans in power with humans that follows them), they were not able to do a simple capture and retrieve, as well as the current status of their ship.
So they first needed to weaking the Demonthans influence and power. That all didn't go unnoticed from the Demonthans and the Angelions Mother Nature. As she know was several hundreds years on this planet, even may be, on some "friendly" terms with Earths own Mother Nature, but all that changed due the influcence of the Angelions. As their Mother Nature doesn't want to be find, captured and retrieved she use her power to avoid that and in this comes in conflict with the Earths own Mother Nature. Perhaps the ten biblical plage came from her?
Thus after many more hundreds years, the Angelions Mother Nature and the Eraths own Mother Nature relationship has turned sour and Earths own Mother Nature turned from somehow friendly or apathetically to angry and hostile.
The Angelions may even use the "going rogue" of the "Demonothan" Mother Nature as a way to gain favour with the Gaians deithy and humans and certain hide their own agenda and the real origin of the alien Mother Nature.
So, I know, if Jack follow, I double (or even trippeld) his work.
In this concept, what would they look like?
And I'm very bad with that.
Question back, do they only have one look or could they be some "Zeus" type that can change form at their will? And eg. be a deer, a bear or any other native lifeform from their respective fauna?
Only going for the Human/Angelions/Demonthans form for now.
Angelions ones should be older one, around mid-fifty or older age looking (same would go for the Demonthans one). Perhaps some scars from her escapes, journey and ongoing conflict with the Angelions. She also should look distinctive different that the "classic" Angelions, but have some traits of them. I she can be categorised into lesser Angel or Archangel, she would clearly be the last one.
Hair, hair colour, eyes and the rest, I let if open for Jack ot someone other to be filled out.
Their Human counterpart shall be younger than the Angelions or Demonthans Mother Nature, that would make her around mid-thirty to mid-forty or near fifty, but clearly younger than the two others.
Her look should be influence by heir thoughs and the status of the nature on Earth, so as she is clearly somehow mad and I would loosely base her on the concept on the character of Alice from American McGee's Alice respective Alice: Madness Returns.