First of all, I want to say that I don't actually subscribe to the Solar Empire/Lunar Republic politics, but it ended up fitting the concept of this picture so well that I decided to use it. The actual idea for the image arose from the fact that Parasol (the name of the pegasus) means "against the sun" in French, and the rest just followed gradually.
I'm leaving what's actually happening here deliberately ambiguous, so feel free to speculate, but I don't feel either side in this is specifically the "bad guy". My own interpretation is that Parasol is a soldier in the New Lunar Republic, which had just overthrown a dangerously inefficient (though not actually malevolent) Solar Empire regime, and Celestia has been imprisoned for her part in running the empire.
This was my first try at doing a comic, and I may decide to do others in the future. They won't be continuing this specific subject though.