Arthur Bernard was a recently-freed slave that was charged of treason as Tarleton believed he knew or was the revolutionary author posting propaganda against the British under the pseudonym Cicero.
Bernard was believed by Colonel Tarleton to be the propagandist Cicero, who had posted multiple anti-British propaganda. They found him inside of his home with him denying he knew Cicero. Tarleton ordered Ichabod Crane, while he was still a British lieutenant, to interrogate Bernard until he cracked. Katrina arrived just after one of the interrogations as a Quaker friend to treat Bernard's injuries. Crane had him interrogated and tried to be nice to him but Bernard refused to crack telling him the rumors of the secret war with demons is true. Crane was then ordered to take Bernard into the woods and to kill him. Crane pretended to shoot Bernard allowing him to escape. Bernard thanked him telling him they will meet again and that the password to join is "orda ab chao" or order from chaos. Ichabod then asked if Bernard really was Cicero. Bernard said that "he is all of us." Bernard turned around and was shot in the back by Tarleton. The Sin Eater takes on his appearance later on in the episode to break the connection between Ichabod and the Headless Horseman.