"Marc" or "Marc (Tartarus)"
Talk about it here.
A slave to Cicero, Marc was freed by his master during an adventure with the Fifth Doctor, Tegan Jovanka and Nyssa, during which he accepted the offer of joining them in the TARDIS. After some adventures, he became a Cyberman.
Marc served as a slave to Marcus Tullius Cicero in the 1st century Roman Republic. He was devoted to his master and spoke highly of him, (AUDIO: Tartarus) sometimes accompanying him to the colosseums to watch gladiators, where the audience's cheering left an impression on Marc. (AUDIO: Warzone) He secretly taught himself how to read and write Latin and had a superb memory thanks to his having to memorise lists to serve his master. (AUDIO: Tartarus)
Travels in the TARDIS
Meeting the Doctor
By 63 BC, Marc was serving Cicero in Cumae. That year, whilst serving drinks at a party at the villa, Marc met the Fifth Doctor, Tegan Jovanka and Nyssa, with whom he and Cicero were transported into another realm by Tartarus. Marc used his navigation skills to help locate the three keys that they were tasked with recovering, prompting Tartarus to select him as the new leader of the extinct Zorth. During the adventure, Nyssa invited him aboard the TARDIS, an offer that he accepted. (AUDIO: Tartarus)
Marc was given a bedroom aboard the TARDIS, but found himself unable to relax in a large and comfortable bed, instead sleeping on the floor for his first night. His first adventure was to the Space Station Proxima in the 30th century where he helped defeat Kalu. On Proxima, he learnt of the translation circuit, energy, sliding doors and interstitial time. (AUDIO: Interstitial)
In 19th century Ireland, Marc and Tegan slept in at an inn whilst the Doctor and Nyssa explored. Marc and Tegan found and rescued the Doctor and Nyssa, who had been possessed by the Spae Wife. They successfully managed to restore her, with Marc attempting to by reminding her of Tartarus and Proxima. (AUDIO: Feast of Fear)
On Samotis, Marc joined and excelled at the Warzone obstacle marathon, seeing it as his own chance to win a test of glory just as the gladiators did in his time. He outpaced his friends and was sent by the course down its most dangerous trail, resulting in him fracturing one leg and breaking half a dozen of his ribs, causing severe blood loss. He and Tegan were taken to a medical bay whilst the Doctor was taken into custody. In the medical bay, Tegan gave ill-informed consent for Florence to repair Marc, partially converting him into a Cyberman. (AUDIO: Warzone)
As a partially-converted Cyberman
The Cyber-Leader sought to infiltrate human populations with Marc's partially converted body. (AUDIO: Conversion) He lost his sense of self until Nyssa shut down the race, allowing the TARDIS crew to take Marc to the TARDIS (AUDIO: Warzone) where he stayed with Nyssa and Combatta whilst the Doctor and Tegan sought a way to save him. His conversion rewrote his biology, causing him pain.
Combatta studied Marc with the intention of adapting his Cyber-technology to her own ends, prompting the Cybermen to initiate full physiological control of Marc's body and having him kill her. Fortunately, the Doctor and Nyssa were able to hack the mainframe and reverse all mental reprogramming, restoring each Cyberman's memories and allowing Marc to regain control of his body.
In the aftermath, the Doctor took his companions to Callanna and left them behind with a great deal of money, feeling that they needed some time apart due to his guilt over Marc's conversion. (AUDIO: Conversion) The Doctor visited Cicero, but did not tell him what became of Marc. (AUDIO: Tartarus) Marc struggled with his new situation, unable to sleep, not needing to eat and having increased strength and speed, and was angry with the Doctor for leaving him. He and Mison acted as bait to distract Bella and Grumma and allow Nyssa, Tegan and Cott to stop them, after which the Doctor returned for them. (AUDIO: Madquake)
Behind the scenes