In a parallel universe, Gordon Flint was a soldier. He came to view Eric Vollmer's research. He praised Lee's work in genetics, seeing the work which had been deemed unethical and dangerous as a future for soldiers, but he was mutated by the genetic super-soldier experiments Lee had been performing and showed disdain for Vollmer, and didn't have any qualms about giving him to Lee to use as a "guinea pig."
Flint's superiors had no idea what he was doing at the DEEP but they were catching on, so he arrived at the base to collect Lee's research to take to put to use and for further study and to destroy the base. He and Lee had planted a cluster of dirty nuclear bombs around the base. He activated the base's self-destruct shortly after Vollmer had been injected, but when he was infected by the super-soldier formula he began to mutate. In a struggle with Vollmer, one of Flint's arms was torn off.
Flint believed that ruthless men had all it took to make history and showed disdain for people who had opposite values.
For 27 years, Flint remained at the base, mutated and wanting to die. He was left for dead by the Doctor, but he knew the Doctor would return for his TARDIS and so waited for the Doctor to come. Full of hatred for the Doctor, Flint force-fed him the TARDIS key and snapped his neck, causing him to regenerate. He blew up the base. (AUDIO: Full Fathom Five)