Abraham was made general manager of Laurel Grove and first in command during Zephaniah Kingsley's prolonged absences. This was a remarkable turn of events that placed Abraham in a unique situation. Although not unheard of, the degree of authority given to him by Zephaniah was exceedingly rare in Spanish Florida. During his time as manager, Abraham displayed a driving will to succeed at his duties and went to great lengths for Zephaniah and the many enslaved people of the plantation. This was illustrated in 1810 when the St. Johns River militia confiscated the guns, weapons, and supplies of the Laurel Grove slaves, supposedly on charges of possible insurrection. In Kingsley's absence, Abraham stood up and refused to allow the theft, resisting the seizure to the point of his own incarceration. He protested loudly and was arrested for disturbing the peace, spending the next month toiling on a heavy labor sentence. In truth, his only crime was defending Zephaniah's private property.
Abraham showed his bold character again in 1812 during the raid on Laurel Grove by Alachua Natives when he was shot defending the plantation and his fellow African Americans. He recovered from his wounds and was rewarded by Kingsley with property along the St. Johns River.
Abraham and Zephaniah's relationship grew more complicated over time. Zephaniah fathered five children with Abraham's daughter, Flora. This remarkable turn of events placed Abraham in a novel position as Zephaniah Kingsley's pseudo father-in-law. Kingsley eventually freed all of the Hanahan family. The relationship between the two families continued up to and beyond the death of Zephaniah Kingsley in 1843. When Zephaniah moved his operation to Haiti, a result of the changing laws in the now American territory, Abraham moved his family as well. In the new nation of Haiti, African Americans could be free and own property, two things denied to them in the American Florida.
Abraham Hanahan began life as an enslaved child, and ended it as a free and prosperous Haitian businessman, wealthy in both family and land. He was forced to leave Florida in order preserve the fruits of his labors and to provide his family with opportunities to succeed in life that were no longer available in the United States.