Brull was one of several Gatherers who ambushed a USS Enterprise-D away team in 2366 with Regalian phaser rifles on Gamma Hromi II. The Enterprise had sought out the planet, and the Gatherer camp there, as part of a peace overture from Acamarian Sovereign Marouk.
Marouk was attempting to re-integrate the Gatherers into Acamarian society, despite over a century of failed attempts to do so. After speaking with Marouk, Brull was able to arrange a conference between her and Chorgan, the Gatherer leader, that ultimately proved successful and allowed an agreement to be reached. (TNG: "The Vengeance Factor")