Boratus was a Vorgon male from the 27th century who, along with his partner, Ajur, attempted to steal a device known as the "Tox Uthat", a quantum phase inhibitor capable of halting all nuclear fusion within a star.
In order to prevent the Uthat from falling into the wrong hands, Kal Dano, the Uthat's inventor, traveled back in time to the 22nd century and hid it on Risa. Having failed to obtain the Uthat, Boratus and Ajur searched historical records and discovered that Jean-Luc Picard would discover and destroy it in 2366. Traveling back to that point in time, they told Picard that they were security agents and that they wished to retrieve the Uthat for safekeeping. When Picard learned, however, that it was two Vorgons who attmepted to steal the Uthat in the first place, he destroyed it using Transporter Code 14, thus fulfilling his role in history. Failing in their quest to obtain the Uthat, Boratus and Ajur returned to their own time. (TNG: "Captain's Holiday")