u/Honest_Brother2022

Ostania's greatest killer unfortunately has a great enemy who terrorizes her and against whom she admits defeat. Bugs are her biggest opponent.

So far, we know very little about the origin of the East-West rivalry. We do know, however, that an empire once existed, but today Ostania and Westalia are republics that have clashed in what is called a reunification war.

It therefore seems obvious that the empire once encompassed the territories of Westalia and Ostania.

So now we must investigate why Ostania and Westalia separated and harbor such mutual hatred. It is likely that the empire collapsed (for several reasons: abdication, lack of a possible successor, or even a possible revolution).

The divide between Ostania and Westalia may be economic.

In the ship arc, one of the assassins implied that Westalia had a more relaxed relationship with money than the East.

We can assume that Westalia follows a more liberal economic model, while Ostania follows a more statist one.

The divide can also be ethnic or racial. We saw in Loid's flashback, or even among the terrorists of the Canine Crisis, that racism is very pronounced on both sides. Perhaps the difference in culture or ethnicity was a trigger or a pretext.

A third possible divide is the political one. Ostania remains a fairly authoritarian country, with a political police force, repression of opposants, control of the press, etc. Perhaps the West is freer.

My theory is that it's likely that after the fall of the empire, the West opted for a liberal regime, while the East opted for a more statist, more authoritarian one.

The two sides would have fought, and the difference in ethnicity and culture would have been used as a pretext for war.