The paper focuses on Velleius Paterculus' portrait of Gaius Caesar (20 B.C-A.D. 4), rhetorically designed in adherence to the political climate of Tiberian Rome: Gaius excels as a sort of anti-Princeps, and this legitimates the position of Tiberius in the light of the complex dynastic situation affecting the imperial House around A.D. 30. The indirect opposition between Gaius Caesar and Tiberius, within the frame of Velleius' Tiberian narrative, offers the opportunity to consider the work of Velleius not only as merely echoing current propaganda, but also as a work of actual political value