Eli Underwood is the alter ego of Elias Vaughn in Vaughn's second orb experience. His life closely follows that of Elias but in a 1950s context. Eli was a fan of baseball and served in the United States Army during the Korean War. He was married to Ruri and they had a daughter Pria. Eli spent a lot of time away from home at conferences or meetings so missed out on much of his daughters life.
Eli was admitted into the Riverdale Asylum for the criminally insane after shooting his wife. He spent the first night in solitary confinement, the next day he was taken by Nurse Sue-Lyn to see Benny Russell a fellow inmate to be shown around and introduced to the other residents. the two quickly became friends and spent much time in the following weeks in each others company. Through his weeks and months in the asylum Eli tells Benny of his history and his difficult relationship with his daughter, Benny told him that he should not dwell on killing Ruri and should live in the moment. One night, Eli woke up to find the asylum deserted apart from Benny. The two leave the asylum, returning to corporeal existence. (DS9 novel: Unity)
Underwood was later arrested with Russell and taken to a New York Police Department station. Kay Eaton paid the bail for both Russell and Underwood. (ST - The Fall novel: Revelation and Dust)