Vaebn was the Chairman of the Romulan Tal Shiar during the early 2400s. He was a long-standing opponent of any Federation – Romulan Alliances, advocating that the Romulan Star Empire should seek a more hostile position towards the UFP.
In 2407, after Vrih assumed control of the Romulan Star Empire Vaebn set out to aid Senator Terrah in a coup to sieze power. With the arrival of the USS Hades to renegotiate the Treaty of Algeron, the plan went into action.
It turned out, however, that Vaebn was loyal to the new Romulan Praetor, when he aided in the countercoup which inevitably resulted in the death of the Senator.