Romaine was one of the designers of the USS Endeavour's new engine core, when the NX-class ship was refitted to be a Columbia-class vessel. Due to his experience with the new engine, he was selected to be Endeavour's chief engineer.
In January, 2163, Captain T'Pol assigned him and Lieutenant Commander Hoshi Sato to help with the repairs of a damaged Axanarri ship that was attacked by the "Mutes". Because of the extended repair efforts, Romaine was late for the poker-night of the senior officers.
In April of the same year, during the Vertian crisis, he and Sato created a device that could mimic the "Mute"'s magnetic and infrared communication. (ENT - Rise of the Federation novel: A Choice of Futures)
In 2165, during the investigation of the Kir'Shara's theft, the Endeavour was docked at Vulcan Space Central and an agent of the radical Vulcan movement sabotaged the ship's warp engines so it would explode. With the help of Tobin Dax, Romaine was able the find where the engine was sabotaged. After Endeavour manuvered out of the space dock, Romaine vented the plasma and shut down the warp core, saving the ship. (ENT - Rise of the Federation novel: Uncertain Logic)