Joseph Delon

 was a tour guide in the catacombs of Paris, who was recruited by the Cybermen.

History
Delon was 80 years old in 1809, meaning he was born around 1729.

As a young man, Joseph wanted to pursue a degree at the Sorbonne, but his father Marcel Delon wanted him to work with him in the mines of La Porte de l'Enfer (The Gates of Hell). Joseph's mother had moved with his aunt Lydia to Montmartre. In 1761, a golden orb Marcel had unearthed turned out to be a time gate planted by Charles VI on behalf of the CyberFaction. A Cyberman came through the time gate and gave Joseph an implant to recruit him; however, his house collapsed, killing Marcel. In 1769, Delon hid some Cybermen in the catacombs as they were being built, and over the next few decades began to cyber-convert aristocrats under the guise of executing them in the French Revolution.

In 1809, Delon led the Fifth Doctor and Time Agent Tina Drake in the catacombs, and helped the Cybermen capture them in a stasis cage. Drake escaped using her vortex manipulator, but the Doctor remained in stasis until 1944 when the Tenth Doctor freed him. This fully allowed an alternate timeline to unfold where the Cybermen had occupied Paris, if not the entire Earth. Afterwards he resigned to dying, until the Cybermen told him they would grant him immortality via cyber-conversion.

The two Doctors snuck to an archive and went to 1769, where they found a younger Delon pawning the golden orb. Some Cybermen arrived but they and Agent Drake managed to escape and travel to 1761 right before the Cybermen arrived to recruit him. A young Delon witnessed his father being killed by Cybermen, which heightened his emotions such that the implant's emotional inhibitor failed and he was not recruited. Agent Drake killed the Cyberman with her blaster, and the Doctors took Delon to live with his mother in Montmartre, all this negating the alternate timeline.(AUDIO: The Gates of Hell)