Superficially the main conflict between Zaibach and the rest of Gaea is about destiny and (arguably) predestination vs free will.
I say superficially because the case for predestination on Escaflowne is largely a straw man.
Zaibach are almost always evil in their actions, and most of the exceptions can be traced to Folken. The rest can be traced to underlings who would never be consulted anyway. This creates a weight of prejudice such that the viewer is never expected to support the Zaibach view.
Fundamentally Escaflowne is assuming the rightness of free will. The focus is then more on the consequences of, and responsibility for, individual actions within the framework of free will.
The narrative device for exploring this is that Hitomi does not predict the future, Hitomi creates or chooses a future and must bear responsibility for the use of her powers.
In essence Escaflowne is about a 16 year old with a loaded gun and no real training.
Fortunately the 16 year old in question is a basically good kid, but still not someone prepared to deal with what's coming.
This is the source of my polite disagreement with seawasp over Hitomi's willingness to do a (admittedly plot-necessary) tarot card reading in The Secret Door.
In the previous episode, Prophecy of Death, Hitomi was placed in extreme danger when she was hypnotised by Zongi. I believe that, in self defence, her powers unconsciously created the future that killed Zongi.
ie: Hitomi is at least as responsible for Zongi's rather gruesome death as Dilandau. Although Hitomi did make a conscious effort to save Zongi it was always going to be too late once her powers had intervened.
Even though she's not aware of it, I believe that the subconscious guilt from doing so should have made Hitomi much more reluctant to do the reading for Prince Chid.
In contrast seawasp has argued that this was an attempt by Hitomi to take back control of her power for herself. It's a fair argument, but not one that wholly convinces me.
It is worth noting that this wasn't an issue for me the first time I saw the series - the reading worked well for me then when I didn't know the full extent of Hitomi's powers.
So it's possible that I was being overly critical of The Secret Door.
The episodes from Red Destiny to Reaction of Fortune are all about Hitomi learning the rules of the game, about training in how to use the gun.
The tragedy of Naria and Eriya is what teaches Hitomi the price to be paid, and this is the start of the wisdom needed to not use the gun.
In terms of the coming episodes, there will be a lot of weird stuff going down.
The core of these episodes will be Hitomi working out the choices that she should be making as a responsible adult, and then committing of her own free will to those choices.
Ultimately the series will end with a 16 year old with an unloaded gun, and the training to know when (and why) to load it.
Day 1 - Fateful Confession / The Tower
Day 2 - The Girl From the Mystic Moon / Ace of Serpents
Day 3 - The Gallant Swordsman / Death
Day 4 - The Diabolical Adonis / The Hanged Man
Day 5 - The Seal of the Brothers / Judgement
Day 6 - Capitol of Intrigue / Justice
Day 7 - Unexpected Partings / The Chariot
Day 8 - Sub vs Dub
Day 9 - The Day the Angel Flew / Temperance
Day 10 - Memories of a Feather / Ace of Birds
Day 11 - The Blue-Eyed Prince / Knight of Beasts
Day 12 - Prophecy of Death / The Devil
Day 13 - The Secret Door / High Priestess
Day 14 - Red Destiny / The Emperor
Day 15 - The Gender of Escaflowne
Day 16 - Dangerous Wounds / The Magician
Day 17 - Lost Paradise / The Star
Day 18 - The Guided Ones / Wheel of Fortune
Day 19 - The Edge of the World / The Empress
Day 20 - The Gravity of Destiny / The World
Day 21 - Operation Golden Rule of Love / The Fool
Day 22 - False Vows / The Moon
Day 23 - Reaction of Fortune / The Hierophant
Day 24 - Destiny, Free Will, and Personal Responsibility
Day 25 - The Black Winged Angel
Day 26 - Storm Premonition
Day 27 - Fateful Decision
Day 28 - Zone of Absolute Fortune
Day 29 - Eternal Love
Day 30 - Looking Back at The Vision of Escaflowne