The Union of Erebus is a sovereign state which claims the entirety of the planet Earth, though its presence is nonexistent in a large portion of the world which is either sparsely inhabited or entirely uninhabited. Erebus as a combined population of around 26 million humans, 8 million vampyres, 7 million ghasts, and 4 million worgs. The majority of the nation's population is centered in the continent of Europe, though Erebus also has established locations throughout the former Americas and Oceania.

Erebus has its roots in the European Union which predated the Great Supernatural War between humans, vampyres, worgs, and ghasts. Upon the approximated end of civilisation sometime in the June of 2007 with the Battle of New York, humanity was left scattered about the Earth under constant threat of extinction by constant vampyre attack. In the August of the same year, a collection of resistance cells across Europe began to emerge victorious against the vampyres after an alliance was forged with the worgs and ghasts, who had both originally planned to remain neutral though were eventually attacked by the vampyres with the collapse of human governments. As the Western world was the only culture with ancient beliefs in the specific supernatural that existed, only the West was able to survive the War and the global East was left almost entirely uninhabited. The Treaty of Bristol, which saw the end of the war with the defeat of the vampyres, established a union between all surviving groups of sentient beings, known from that point on as Erebus. A direct result of the vampyre's defeat was the World Slip, which saw the reintroduction of ancient magicks with the end of contemporary humanity. Although the world itself was not damaged by the Slip, humanity became much different afterwards, recovering into its current state by the end of 2012.

Erebus is a confederation based upon a loose collection of six sovereign states which have survived past the end of the world. Though not fully politically united, the states exist in a connection of defensive, economic, and basic political principles which unite them under a common banner to coexist in peace and union. There is no single head of state in the union, only a bicameral parliament which is divided into the House of Commons and a House of Senate. The House of Commons has the power to influence common laws and enactments throughout Erebus, while the House of Senate has administrative control over the small central government. Members of both houses are elected popularly by residents of the nation with universal suffrage. The principles of the union are enacted by the constitution, which was passed on 29 February 2008.

The economy of Erebus is considered to be post-material, post-industrial, modern, and highly urbanised. Extremely diverse as it is composed of all economic activity, Erebus has economic presence in all worldly commercial affairs. The single currency of the nation, the Erebusian pound sterling, is considered to be strong and stable. Economically, the single government has eliminated trade and migration restrictions between the various nation states of the world, wholly eliminating the need for tariffs and quotas between global trade. Though the country has an extremely diverse economy, Erebus itself has a strong economic base in service based industries such as finance, telecommunications, and retail. Highly modernised and urbanised, most people in Erebus live in cities with jobs in the service industries. As a post-material economy, capitalism is largely rendered obsolete, and politically, many would consider the economic of Erebus to be a moderate mix between capitalist and socialist policies. As such, Erebus is a free market with high levels of economic freedom and a generally moderate cost of living.

As the single sovereign entity of civilised peoples, Erebus has maintained peace and virtually eliminated the need for conflict between nation states. Racially, humans, vampyres, ghasts, and worgs live together in harmony with an acceptance of each other and a common understanding between their differences. This social harmony has been maintained since the creation of the union with the Treaty of Bristol, which instilled policies rejecting discrimination based on all differences between peoples.