A clone of Ryan Stevenson, Greg is one of 25 'copies' and the first out of the Alterran incubation chambers that they were 'born' in. He has the same genetic structure and memories as Ryan, but a different core energy. Similar in nature to twins, clones are different people in the same 'body,' though over time that body will alter to match the 'person' inside, which is why some twins appear the same 30 years down the line and some will vary drastically in appearance.
Gred, along with his brothers, each assigned themselves to a needed task in the initial rebuilding phase of the rebirth of the Alterran civilization to lessen the load that Ryan had been carrying mostly on his own, choosing to tackle the seemingly unimportant cityship redesign project but he, like Ryan, knows of its long term importance...and how it is something that Ryan will likely never get around to tackling having to deal with one immediate crisis after another.
By taking on the project, Greg is putting one long term 'iron in the fire' while the rest of his brothers deal with varying aspects of Alterran society, mostly in the Pegasus galaxy. Greg spends most of his time in a design center in Ida, the same facility where Ryan and Bra'tac collaborated to create the Columnar warship blueprints.