Captain Flameheart Junior found an Ancient coin in the corner of his room. According to the studies of Flamheart senior, the ancient coins are very old and were once used as a currency on the Sea of Thieves. A pirate would be considered vastly fortunate to have a couple about his person, as they were most often used to accompany promises, oaths or allegiances. Breaking a bond forged with an ancient coin is unthinkable.
Flameheart Junior proceeded to give the coin he found to Isidro, his first Crew member. What exactly happened with the coin afterward is unknown, but the two stayed on the same crew until they were cursed, so the coin seems to have worked.