First off, this is just a collection of my theories about the world of Razia's Shadow, they aren't necessarily canon. However, for all of my fan fiction, I treat them as canon, so here it goes.
This is part is about the differences between the Dark and the Light. I didn't think it was very black and white, the Dark being completely bad and the Light being oh-so good. The whole point was that the world was separated and split like a cloth, since they used the metaphor of sewing so much. They made it seem like the two needed to be together, just like cloth needs to be sewn together to work.
I like to think of it, clichély, as the whole ying yang thing. There has to be a balance. Good cannot exist without evil, and evil cannot exist without good. Specifically, here's my theory.
I think that when the two halves split, something happened to everyone in their respective kingdoms. For those citizens of the Dark, they lost all restraint on their emotions, much like Ahrima did. It's not that they had all bad emotions, they just didn't know how to control them. You get angry, like Pallis did at Adakias, you let that anger rage out of control. Even Adakias is kind of unrestraint-y, as he doesn't hide the fact that he hates living in the Dark, then acts rashly on these emotions by running away. The bad thing about this, obviously, is the situations with the negative emotions running rampant as in Pallis' case, but it can be good with positive emotions. Think of unrestrained happiness, for example. Another good/bad thing is that everyone is totally honest. If you don't like someone, you tell them. Honesty, though can also be bad in certain situations when it is better to lie (can't think of an example, it's 1:30 in the morning). The whole honesty thing could also lead to no regret, another good/bad thing. Bad if you don't regret hurting people, good if you don't regret doing good stuff that may have ended badly or something. I don't even know. Hopefully, you're making sense of this ramble.
As for them Light folks, I think that they ended up, out of fear of becoming like Ahrima, restraining their emotions too much. This is bad and good, just like the Dark (I wasn't kidding when I said I thought this was a gray subject). The restraint means that people's feelings can be saved, but this also means potential lying gone rampant just to make other people feel better, which is not a good thing. It also means no expression of true feelings, meaning they get bottled up inside. I imagine (or this may be canon idek~) that the Light sent all their "crazies" and criminals to the Dark, but if the Light is supposed to be perfect, why might they have cracked? Because they had their emotions all bottled up! The bottling up could also lead to apathy, which is worse than love or hate. Even with hate, you're showing a strange form of caring for someone, but apathy is where you don't give a flying whoop whether they live, die, are happy, are depressed, whatever. And I'd also like to state right now that while these have potential sociological reasons for happening to the citizens of the Light and Dark, I also imagine there was a big of magic to it. Especially with my physical theories about the two.
I imagine the Light and Dark to be literally, light and dark, with the Dark being completely black and always nighttime with a constantly full moon to give some light and then also the stars, and the Light being always daytime with the sun up. I also imagine them to be geographically opposite, with the Dark being tundra and the Light being desert. However, with Adakias' death and the fall of Razia, I imagine that the two's climates would (through magic, of course) intermingle and balance out to a more moderate, temperature geography and climate. Along with this, the people's psychological problems would be fixed, and both would experience normal patterns of night and day, sunrise and sunset and such. Yay!
On another, slightly less important side note, I imagine most of the people of the Dark to be fair in skin tone with dark hair and eye colors due to the lack of sunlight, with the people of the Light being just the opposite, darker in skin tone with fair hair and eyes due to overexposure to sunlight. It makes sense, even to those of you who don't know biology. If you stay outside lots in the summer, your skin gets tan and your hair gets lighter, whereas in the winter, you pale up and your hair gets darker. Also, this was slightly based off the character artsies. Pallis is pale with dark hair, Anhura is tan with light hair, and then Adakias has tan skin and black hair (I attribute the tan-ness to his Light citizen disguise - you know, "Disguised as a citizen, his identity was hidden…").
That's about all for this round. I'll be posting some more of my theories in later "chapters," but I just wanted to get this down for the record. It saves me a lot of explaining in my fan fiction if everyone just refers to this then reads it. Helps me get to the point of the story easier, especially since I try to get to the point very quickly. Thanks for reading!