Suso

 was a scientist on the Schrödinger Institute and an agent for Galextricity Corp.

As an agent for Galextricity Corp, which provided energy for an unknown planet, Suso, along with fellow agents Fauler and Van Ruysbroeck, objected to Tasdevin's proposal for a perpetual-motion machine. Their objections increased when they learned Tasdevin was trying to stabilise space-time in order to make himself immortal.

When Tasdevin's experiment caused a temporal echo in which the Doctor and Guinevere Winchester were trapped, the Doctor and Guin witnessed echoes of Suso and the others trying to stop Tasdevin. The echoes faded away when the Doctor ended the loop. (PROSE: Revenants)