Hickey was born in Ireland but immigrated to the Thirteen Colonies, where he enlisted in the British Army in 1754, fighting in the French and Indian War alongside General William Johnson, a fellow Irishman who was the commander of a large British army in the Ohio Valley.
One day, he met with Haytham Kenway, a member of the Knights Templar, and joined him alongside William Johnson, Charles Lee, Benjamin Church, and John Pitcairn. Hickey suggested that they murder General Silas Thatcher, a British officer in charge of the Southgate Fortress, who was involved in the trafficking of the Mohawk, in order to find out the Mohawks' secret lands. They succeeded, with Church shooting Thatcher in the forehead after he was captured in the storming of the fort in 1756. Afterwards, he worked with William Johnson in smuggling tea into the Thirteen Colonies, especially after the Stamp Act, which placed the price of tea higher, and they made a mint off of selling tea for cheaper prices.
After Johnson's death in 1774, he became a solo counterfeiter, and in 1775, joined the Continental Army. In 1776, Haytham Kenway told him to murder General George Washington so that Charles Lee could become General, and he joined his private guard during the Battle of Brooklyn Heights and many other battles in New York. However, he was arrested after brawling in the streets of New York, with Connor Davenport, a Mohawk assassin who was an enemy of his kind, the Templars. When Connor found a way out of his cell, he attempted to kill Hickey in his cell, but found a random dead body, and Hickey and Lee appeared behind him, knocking him out. Lee used his status as a General in the Continental Army to persuade the court that he was plotting to kill Washington, letting Hickey off scot-free. However, there was no trial, and he was sent immediately to the gallows.
DeathHickey escorted Davenport to the gallows, a hanging which General Washington himself attended, alongside Lee and many civilians. A woman punched the man in his face and spat on him, but Achilles Davenport approached him and told him that he was there. When he was about to be hanged, Achilles cut the rope as he reached the bottom of the noose, and Connor, equipped with a tomahawk, chased him to an arch, where Hickey attempted to attack the Continental troops guarding Washington. Hickey was hit in the chest by Connor's tomahawk, mortally wounding him, and as he died, he revealed that he did not understand about the reason why the Templars supported the British, and revealed that he was paid by the Templars, and did not ask any questions, and that "principle cannot be brought to the bank". He insulted Connor about his status, before dying on the cobblestone street.
Connor was then nearly arrested by several Continentals, but General Israel Putnam spoke in his defense, and the guards let Connor off.