He and his lover Kedin Ashar made advanced weapons for Vethran in exchange for his promise to fund their further research. Vethran used them to expand his power over the planet and attack its neighbour, Mendeb Two. He kept Roslod as a prisoner to ensure Ashar's continued cooperation.
When Ashar led rebels to overthrow Vethran, Ace was able to put some of the mind control drug SS10 into one of his drinks. Rendered a virtual automaton, Vethran's reign over the Mendeb system was ended. However, Roslod had also been given the drug, whose effects were irreversible. (PROSE: Independence Day)