The Blessed War

5

We can think of the Divine timeline as a sequence of four eras.
The First Era was the Era of Creation. Very little - if anything at all - is known what happened in this era. It describes the creation of each realm and the species allocated to it, a period of time long forgotten.
What exactly caused the creation of the realms lies beyond common knowledge, but here's my viewpoint.
The responsibility lies on life force. Once life force .. happened, so did each realm.
The Angelic realm was very much overflowing in heavenly light, and life force began to collect strands of light into Angelic beings. These beings were immortal because light doesn't decay.
In the Fairy realm, plantlife flourished immensely across the whole realm. And when it did, not only were Fairies born out of nature, but nature itself began to work with life force to create the wildlife we know today.
The Unicorn realm was once nothing more than a void. Life force changed that dramatically. Once life force began to intervene, what can only be described as a boom swept over, materialising the realm and its Unicorns. How exactly did a realm grow out of nothing? ... I'll get back to you on that one.
But keep in mind, that's just my stance. There a several dozen ways of seeing what happened in the Creation Era, and much is still under dispute.

Next came the Second Era, the Era of Uprising. Each realm's governing species soon grew familiar with their realm, their magic and their own selves. They began forming their own cultures and customs, established at the heart of their respective communities.
The Angels couldn't help believing there was some mystical entity beyond their scope of understanding that created All things. They proclaimed life force was thanks only to this entity, and out of honour and gratitude, the sole duty of Angels was to worship this Highest Power for the rest of their indefinite lives. Their magic really complemented their religious manner. Though it was independent of life force, it was believed that their magic was as sacred a gift from the Powers That Be.
The Fairies were born tied into the Web. Their life force seemed less of a blessing to them and more symbolic of their connection. Nonetheless, it was still considered a sacred force and the Fairies were highly thankful. They honoured everything by enriching the realm with their spell-casting. Without plantlife, the Web would have no abundance of life force, and without the Fairies, plantlife wouldn't have the vitality it does. It was a happy cycle where everything flourished, just like a fairytale.
... Heh.
The Unicorns took a while to gather their bearings. Surrounding them was a bleak landscape; endless rock, desert and marshland was scattered all around. However, the first thing they did was explore. The most powerful Unicorns of the time were much more concerned with the nature of magic, so instead of venturing the sprawling land, they begun sculpting the podium from small, gentle fragments of raw power, bound together into a huge crystalline centrepiece. And as if on cue, soon after a band of explorers returned, carrying with them a heart-shaped gemstone, pulsating an eerie kind of energy. Thus, the Heart became the power source of all the realm's vitality and stability.

This Third Era was an important part of nearly all the history of the realms.
This Era is named the Era of Unity.
Now, up until this point, no realm knew of any others, until a strange portal appeared in each realm... as cliche as that sounds.
A long distance away from each realm's established settlement, strange magic skewed the very fabric of space. A cavity appeared in some mountainous outback; by chance, each cavity formed within some kind of cave. Although, this meant the cavities were cleverly hidden to do what it did next.
Each one sapped on each realm's magic; it sapped light out of the Angelic realm, it sapped life force out of the Web and it sapped the Heart's power. The actual effect was unnoticed until the portals themselves were discovered. Luckily, no harm came to the species of each realm, though none knew what to do next. This magic was truly foreign: dark, greedy and uncontrolled.
It perplexed the Angelic Council, the Fairies were fretful and the Unicorn King and Queen tried several ways to close up the cavity.
But then it just... stopped.
The small space-fractures cooled off from draining all the magic they could, but whether this was thanks to their efforts or something unrelated, but there was no way of knowing. It was unsettlingly abrupt.
And not only did they cease their theft.
The portals now acted as some sort of, gateway between world this world and some other...
Beyond the gateway was a wondrous place. It was abundant in Angelic light, the Heart's love and forests like those the Fairies lived in.
And there, all Divine came together. Immediately they began to mingle and befriend one another, and those with particular talent and interest in magic formed a unified branch in this realm.
They named themselves the Band of Divine Scholars. BODS for short. We named the realm the Centric realm.
And so the Era of Unity began.