The Xephix Empire
The Xephix Empire is a militaristic monarchy from the Xephix homeworld, located somewhere unknown. However, the Xephix have conquered several alien worlds over the course of 31 solar cycles, the Xephix equivalent of 27 Earth years, under the leadership of King Sentia. Sentia's son and prince, Chirns, is the commander of a large fraction of the Xephix armada. Due to overcrowding and shortage of hospitable planets to colonize, the Xephix find the planet Earth, and scan it for resources. Much to their delight, Earth contains the right amount of resources to keep the Xephix going, as well as room for many colonies. However, there was one threat to their dream of colonization: the human race. The empire sets off to vanquish the humans and take Earth for themselves, which leads to the events of Sonic Adventure: Exodus.
The Xephix Empire's history dates back to sub-ancient times, where several civilizations where growing across the universe, such as the humans and Wisps. As the species evolved, their average intelligence rose twofold. Over the course of hundreds of years, the Xephix became the smartest species in their galaxy, already establishing fleets across the Xephix homeworld's atmosphere. Several Xephix leaders rose up in the ranks, with imperial and supremacist beliefs in mind. A revolution then took place, and ended in imperial victory. Due to propaganda and display of military strength, the Xephix became hostile towards other worlds, willing to take their resources, homes, and people with force. Around the events of Sonic Unleashed, the now sprawling Xephix Empire had caught a glimpse of the Earth, several lightyears away. Seeing that the thriving planet was more resourceful than worlds captured in the past, the Xephix began a full-blown mission to take the Earth to assert Xephix dominance across another galaxy.
The Xephix hierarchy was originally pure-hearted, but eventually grew corrupt with the rise of supremacist minds in the council. After the Great Revolution, 13 Xephix solar cycles ago, the imperials were in the driver's seat of the Xephix council. Despite many leaders taking over as "king," they have been assassinated by rebels who tried hopelessly to regain control of the Xephix government. After the "cleansing" of anti-imperialistic rebels, the Xephix council crowned king one of the founding members of the Xephix Imperial Party, Sentia. Sentia grew the Xephix military in hopes of conquering foreign worlds to strike fear across the universe. His dream became true; over the course of 31 Xephix solar cycles. In the second year of conquest, Sentia married an unknown bride, who gave birth to his son and prince, Chirns. Sentia swore that in the event that he would perish with or without notice, Chirns would be his heir to the throne. By the time he became an adult in Xephix solar cycles, Chirns was given near complete control of the Xephix military. The aging Sentia had spotted a planet, several lightyears away that would provide resources to the Xephix people. The Xephix armada go on to forcefully capture and colonize Earth, leading to the events of Sonic Adventure: Exodus. [Finishing article later.]