Diarchy believes in a system where two people, either lawfully or de facto, share the same title. This is not to be confused with a dual monarchy.
History
Where Diarchy's history starts is uncertain, however it can be assumed to be one of the oldest forms of government in the world. Presumably starting in Ancient Greece, many countries used the diarchal system, including Sparta. During the days of the Roman Republic, the RR used a diarchal system as a counterbalance between the Consuls, not allowing each other to gain too much power over the other.
Medieval Europe saw much use of the diarchal system, where two rulers ruled over a single piece of land. The only remnants of this are Andorra and San Marino. Japan, Siam and Tibet used diarchal systems as well. The British commonly used a Diarchal system in their colonies as well. Only a handful of countries today still use the Diarchal system.
Relationships
Friends
Roman Republicanism - Based dad.
Oligarchy - Other based dad.
Tetrarchy - Like me but twice.
Frenemies
Athenian Democracy - Athens weak sparta stronk.
Stratocracy - He protecc but he also attacc.- Literally every ideology with a single ruler - You're half of me, I don't know what to think of you.
Enemies
Itself - I am my own worst enemy.
