Paolo was a Quinto in the Army of the Jihad, and an aide to Primero Xavier Harkonnen on his visit to Tlulax. While there, Harkonnen learned the horrific truth that Grand Patriarch Iblis Ginjo had been hiding for decades from the League of Nobles; that Tlulaxa slavers had been harvesting soldiers of the Jihad for their Organ farms, instead of growing the organs themselves.
Xavier explained his plans to Paolo, and sent Paolo back to human space in a spacefolder Kindjal with a message to Primero Vorian Atreides. Xavier then commandered the transport ship with himself and Ginjo on it, and headed it towards the Thalim star, killing thus himself as well as freeing humanity from the criminal Patriarch.
Soon afterwards, Paolo delivered the message from Harkonnen to Atreides on Caladan, who tried to clear Xavier's name, but it was to no avail. Due to subsequent machinations of Iblis Ginjo's political allies, and his widow Camie Boro; the truth of that event was distorted: Iblis was eventually revered as a martyr and Xavier was marked as a traitor. Vorian Atreides and Paolo were the only ones who knew the true history.