"Arcadia is less of an organization and more of a family, or an immortal body. Those who disobey their tenants are 'punished' as children are, and cutting the head off of Arcadia only ensures swift retribution."
—The Nature of Shadows, Volume 1Arcadia (Or more popularly known as the Arcadian Church to those unaware of its true purpose) is a massive gathering of highly skilled assassins recruited from all walks of life. They are, currently, the oldest and most 'well-known' assassins in the world, but those who speak of Arcadia are generally dismissed as believing in idle rumor.
Arcadia was established long ago by servants to a tyrant that would drive his people to hunger, or throw them into wars with that same threat hanging over their heads. With no lands of their own, they took on the name "Arcadia" in promise of bringing paradise to their collapsing kingdom. Arcadia loomed over the king as a foreign army with unknown numbers, but as he prepared to fight a false war, his rule was overturned and collapsed from within as Arcadia secretly pushed themselves into power, and the tyrant king into death. The lands of the kingdom were split among the three who had spawned the idea, and as promised, they brought forth peace through subterfuge and bloodshed.
Heroic though their ideals were, trickery and shadows earned them their respective thrones, and Arcadia could only grow from these early assassins. Though the brothers were not initially eager to do so, they were called upon to consolidate their power, or risk being overrun and have their fledgling kingdoms ripped out from under them. The three met in the eve and discussed how they would do so with armies consisting of peasants alone, and could only think of a singular solution. They could not train warriors given that they were not soldiers themselves, but they could build an army to do as they had done to free their kingdom from its original reign. Thus, the original Arcadian Church was born. As it had been years prior, Arcadia's symbol served as a rallying cry for the paradise sought by the brothers.
They sent the new assassins out as holy men, and envoys of the Arcadian Church, an unknown name in the world. Though still a young organization, Arcadia celebrated its victory after witnessing nothing happen. To some, no change would indicate nothing, but to the three brothers, they realized that nothing happening meant their plan succeeded. To hear their assassins tell the story, the young kingdom was to be taken, but the royalty on the throne "abdicated in favor of another" before they could reveal their plans for a campaign. Arcadia had put puppet rulers in place by taking advantage of child rulers who had no choice but to listen to their 'advisers.' Though the kingdoms they would have become embroiled in war with over land never ended up crossing them, Arcadia had won an invisible war, and taken over while silencing any voices that could be heard through seemingly random acts.