Human (The Edge of Time)

A human became a companion of the Thirteenth Doctor during the Reality Virus crisis that wiped out most of the universe. (GAME: The Edge of Time)

First adventure
The human had helped the Thirteenth Doctor defeat the First's Reality Virus before being dropped back off, unknowingly in a time loop where they'd have to be recruited again. (GAME: The Edge of Time)

The Reality Virus
The human was in a London laundrette in the 21st century when the Thirteenth Doctor began to communicate with them through the PA system and eventually a television, detailing the events of a universe ending Reality Virus that has sent her to the edge of time and the universe. Recruiting the human, the only person who can help her save the universe, time glitches for them, sending them to an Earth invaded by the Daleks and Hydrorcs.

They enter the office and gets access to the Doctor's sonic screwdriver to help with the mission. They then put together a makeshift device in order to summon the Doctor's TARDIS. This however attracts the attention of a Dalek saucer, causing them to make a quick getaway.

Once in the TARDIS, the Doctor briefs her on the situation, needing to cobble together a vortex manipulator, however requiring three pieces of Zeiton (or time crystals) to power it. The Doctor walks them through tracking down the first piece.

The TARDIS winds up on the SS Lucia Minor where she meets Emer, someone who seems to be familiar with both them and the time glitches. Time glitches again, sending them into night where there are Tazmas lurking around after the Zlysters attacked the ship. Emer guides the human through the ship, equipping them with a torch, until they reach the flight deck. The Doctor regains communication, revealing that Emer was the ship's emergency life support system the entire time. The Zlysters then plan to create a supernova using the ship, which is stopped by the trio. Emer ejects the time crystal. The human escapes, but not before sonicing Emer.

Back in the TARDIS, the Doctor reveals that they rescued Emer, who now communicates with the human via the nano-translator in their brain.

Eventually they go to London in the 19th century where the Doctor believes the crystal to be in the time cabinet of Magnus Greel. They exit the TARDIS and into the dishevelled and broken home of Sir Manfred Grayle, a collector who through a phonograph recording expresses familiarity with the human, claiming they've invaded his home many times before. As it plays, time glitches to a time where the house was in pristine condition, and then back to its state of disrepair. He reveals that the cabinet is protected by Weeping Angels who kill him, and taunt the human and Emer.

As the phonograph is connected to the time glitches, the human is able to travel back and forth in order to open the lift to the crypt. They activate the cabinet using a Trionic lattice and take the next time crystal, but end up having to fend against the Angels in the crypt and keep a generator running. Eventually they escape into the TARDIS.

They land on Metebelis IV but the Doctor first explains the origins of the virus, pertaining to the first sentient lifeform known as the First. They exit the TARDIS and almost immediately find the time crystal, before time glitches to a moment where the Daleks have invaded. The human navigates through the planet before going inside a Dalek casing - Emer controlling the movement and the human taking control of the shooting. With this new ability, they're able to stop the Daleks harvesting the power of the time crystal and take it for themselves, time glitching back to an invasion-less Metebelis IV.

As they put the crystals together, the rock slab opens up revealing the TARDIS inside, and walking in reveals that the console is gone, and the TARDIS is dead.

The duo wind up in the Inner Temple of the First, coming face to face with the universe destroyer. The Doctor then reveals that she didn't actually need the Zeiton but just needed them to visit all the locations and be familiar enough with them to mentally go back and collect pieces from each of them to form a device that banishes the First. This however creates a time loop as she will come back to attempt her plan again and thus the human always needs to be there to stop them. (GAME: The Edge of Time)

Other loops
During other adventures in fighting the First, the human wrote a journal with helpful information on several species and locations that might be helpful and scattered the pages throughout. Edited by Emer and the Doctor, together this document was called the Journal of Improbable Things (GAME: The Edge of Reality)

Battling the CyberReaper
The human once again went through the loop to defeat the First, though it was slightly different, as throughout the figure of a Cyberman keep appearing. In the 21st century, the human had to evade Dalek saucers and subdue a Dalek before summoning the TARDIS. In the 19th century the TARDIS didn't land inside the house and when in the crypt the human had to walk through the corridors before finding the cabinet. On Metebelis IV, they had full control of the Dalek casing. Eventually they were once again dropped off in the laundrette, the Doctor noting that something's changed.

Emer notes that the Virus hasn't been wiped out and that a version of it is still active and strong. When they activate the PA system, instead of their Doctor speaking it is the Tenth Doctor. He reveals that the Cybermen are in charge of the Virus and send the duo to stop them. Telling them to find the head of a Cyberman to find out more information. Evading Cybermen patrolling the area, they find out information that the Virus was reformatted using Mondasian technology. It sends a warning to the Cybermen of their location but Emer transmats them successfully into the Cyber Warship.

They navigate the corridors to find the Thirteenth Doctor imprisoned due to forming a telepathic link to the Cyberium. The human and Emer find a Cyberarm and free the Doctor. An alarm blares and the ship changes designation for mass conversion, so the Doctor remains to interrogate the Cyberium whilst the duo are left to find a way to lower the forcefield and allow the TARDIS in. As they do so, the figure of the Cyberman is revealed to be the legendary CyberReaper who chases them. They make an escape into the TARDIS.

The Doctor reveals that the Cyberman have three transmitters that allows their Virus to be so powerful and that they need to be destroyed. Time glitches, taking them to 22nd century Mars, but everything is glitched and chaotic. The Tenth Doctor appears and runs with the human away from the CyberReaper to the first transmitter which they both destroy with their sonic screwdrivers. After this, they are catapaulted into another weak spot in reality and destroy that transmitter.

Appearing at the last weak spot, before the human reaches the transmitter, they meet up with the Thirteenth Doctor and the CyberReaper who discuss. The CyberReaper reveals there were new realities created by the Virus - such as one where the Tenth Doctor stayed with Jeanne-Antoinette Poisson. Unable to find herself strong enough to destroy the final transmitter, the human destroys it for her. With the universe restored to normal, the human is dropped off at the laundrette. (GAME: The Edge of Reality)