Finally doing my GM duty. Sorry, Echo, Syn, to keep you all waiting.
There are 2 main things in her bio you should think about.
1- Problem: Since Surface was only created when the humans were created, it’s impossible for her to have inhabited it prior to their creation.
Solutions: She COULD, however, have been in a region which wasn’t populated immediately. Alternatively she could have been a Weather in Heaven and then dropped on the Surface during the Great War where she continued her duty. Lastly, you could say she was one of the first settlers of Surface (which means she must have been killed in Heaven and been reborn on the Surface OR she convinced Chime to let her through the gate (she only would if she knew Cerria would not cause any trouble for the humans).) You could also say she didn’t mind the humans at first because they were weak and lived in peace with nature.
2- Why the pollution of her land affects her. I would say since both radiation and CO2 exist in nature you could say that it’s the misplacement or increase of concentration of naturally occurring elements that affects her (like an overdose). Or if it’s brought from elsewhere – the intervention/injection of another essence in her own (the essence of another weather angel or a human one (artificially created) that seeps into her through her land.) Additionally, Yoshu mentioned that perhaps she's abnormal because she's an archangel/weather angel at the same time, causing a deeper resonance/connection with her environment's state/essence than is normal which results in her being affected.
* Why can she move about freely?
a) Since the fall of Hell’s gate the regions the Weather angels gain their powers from (above Rifts in the void) have been expanded and now cover most of the surface world.
b) The radiation that’s become a part of her has spread far and wide.
c) Since she’s not a pure Weather angel but also an Archangel.
Additionally I should point out that you shouldn’t worry about her moving around – this RP barely ever involves any travelling so even if she’s bond to a certain region you can still interact with us freely if we say the story is set exactly there.
Social Status: Outcast - As a Weather Angel Alluvia was left to her own devices by most Angels and largely unknown to others. Since leaving her own land she has retained this outsider nature, though her tendency to unleash the destructive forces of nature wherever she goes has given her a fearful reputation.
I’d also add that the Council had made a few attempts on her life but always failed. (they were devoted to protecting the humans but very very few of them could take on a Weather. You could use that as an interesting retrospective side-story.)
Also, this is something you won’t find written anywhere but it’s just a by-passing note and an unwritten rule. When referring to the essence that’s in all things we write it with lower case “e”. When it’s “Essence” with a capital it refers to a specific creature that was created some 225 years ago from the remains of Heaven’s gatekeeper Chime and her Violin. That creature was what was dubbed “Essence of the world” since it could alter reality.
All in all, I really liked your CS. I don’t think there’s too much to worry about. I saw Syn went very in-depth with the lore (which I’m eternally grateful for) but your own attempt wasn’t too far off anyway. I hope you have enjoyed reading it still and found it somewhat interesting. So yeah, just add or alter a few sentences and I think you’ll be fine. ^^
Can’t wait to see your character in action – I warn you that with her temper she might get more enemies than friends if she ends up causing the same havoc in the city S2 is set in.
(Which we have to decide upon actually………)