"Marc" or "Marc (Tartarus)"
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As a Roman slave
Prior to meeting the Doctor, Marc was a slave to Marcus Tullius Cicero. He secretly learned to read and write in Latin. (AUDIO: Tartarus) Marc spoke highly of his master, to whom he was devoted. (AUDIO: Tartarus, Conversion) He sometimes accompanied Cicero to the Colosseums, where they watched gladiators fight in the arena. There, audiences cheered the names of victors, leaving an impression on Marc. (AUDIO: Warzone)
Meeting the Doctor
In 63 BC, while serving drinks at a party hosted by his master Cicero, Marc met the Fifth Doctor, Tegan and Nyssa. He was transported to another realm alongside the Doctor, Tegan, Nyssa and Cicero. He used his navigation skills to help locate the three keys, and after this adventure Cicero decided to make him a freedman. During their adventure, he was invited aboard the TARDIS by Nyssa. (AUDIO: Tartarus)
Travelling in the TARDIS
Arrival on Samotis
When the group arrived on Samotis, Marc took strongly to the Warzone obstacle marathon, quickly outpacing his friends. He felt that this was his own chance to win a test of glory, as had the gladiators in his own day. The course adapted to send Marc onto its most dangerous trail. Tegan caught up with him, having taken some shortcuts. Unaware that registered runners had wristbands to temper the extent of danger they faced along the track, according to pain capacity, Marc plunged himself into danger time and time again, with little thought for consequence. He and Tegan worked as a team to advance past obstacles.
At one point in the trail, Marc convinced Tegan to advance with him into the Death Spinner. They passed the first spinner with ease, avoiding its rotating columns of electricity simply by timing their approach on a count to three. However, against Tegan's urging, Marc proceeded to dive into the "Big Dipper", an underwater cave, whereupon a robotic eel grabbed him, fracturing one leg and half a dozen of his ribs, and causing severe blood loss.
The Doctor arrived in time to pull Marc out, and Tegan performed CPR as the race stewards arrived in response to the crisis. The Doctor was taken into custody along for refusing to leave Marc's side, and Marc was taken on a stretcher, along with Tegan, to a medical bay. (AUDIO: Warzone)
In the Warzone med-bay, Tegan gave ill-informed consent for med droid Florence to repair Marc, her "counterpart". Marc had been assessed as a candidate for "qualification", due to the remarkable resilience he displayed in the race. With life signs at 22%, Marc awoke briefly and assured Tegan that he would be alright. According to Florence, however, an upgrade to 200% of his original condition was the minimum for such an operation. Tegan tried to stop her, but could not revoke her earlier consent. Unknown to all, this medical upgrade was an adaptation of Cyber-conversion technology. (AUDIO: Warzone) The Cyber-Leader sought to infiltrate human populations with Marc's partially converted body. (AUDIO: Conversion)
With the tune-up completed, Marc was released from medical care, now physically stronger. Following his conditioning, he rejoined the race with a renewed vigour, intent on reaching the finish line to achieve qualification for a full upgrade. He ignored Nyssa when she called out to him. Eventually, Tegan managed once again to catch up with Marc, but failed to convince him to stop. Meanwhile, on the Doctor's instructions, Nyssa shut down the race from the inside. Only then did Marc stop running, as he began to regain his sense of self. Hurriedly, the Doctor and company returned to the TARDIS. (AUDIO: Warzone)
Though he knew it should be impossible to reverse Cyber-conversion once the process started, the Doctor, overcome with guilt over the death of Adric, refused to lose another friend to the Cybermen. He left Marc with Nyssa, in the care of Combatta, a medical researcher, while he and Tegan pursued a means of saving Marc elsewhere. When he again regained awareness, Marc fought against his psychological conditioning by holding on to his memories and personal motivations. To the Cybermen, Marc's consciousness was "irrelevant input" in the mainframe; his continued presence was described as "ghosting". Marc was in a great deal of pain as Cyber-conversion rewrote his biology.
Meanwhile, Combatta intended to study Marc and adapt his Cyber-technology to her own ends. As she proceeded with her invasive analysis, a transmitter in Marc's cerebellum detected that he was under attack. The Cybermen initiated full physiological control of Marc's body, and he killed Combatta. Later, the Cyber-Leader and Cyber-Lieutenant arrived, but Nyssa took them out temporarily with medical nano-drones. Inside the mainframe, Marc exclaimed gleefully that even if this was the end, he would die a free man.
On the Doctor's return, having hacked the mainframe, he and Nyssa employed the nano-drones to reverse all mental reprogramming, forcing each Cyberman's original memories to return. As a result, Marc finally regained control of his mind and body.
In the aftermath, the Doctor took his companions to Carlanna. Filled with regret, the Doctor left all three of them behind with a great deal of money, as he felt they needed some time apart. (AUDIO: Conversion) The Doctor later visited Cicero and would not tell him what had become of Marc, only saying that travelling with him was sometimes dangerous. Cicero asked if it was fatal, but the Doctor said nothing. (AUDIO: Tartarus)
Behind the scenes