The Doctor's reality (The Eight Doctors)

A sequence of events in the Eighth Doctor's life spanning his travels with Sam Jones to his travels with Fitz Kreiner and Trix MacMillan shared a continuous reality with many mostly standalone adventures of prior Doctors, (PROSE: The Eight Doctors - The Gallifrey Chronicles, The Devil Goblins from Neptune - Atom Bomb Blues) with one account indicating this reality was named Earth-Prime. (PROSE: Spiral Scratch) This period had frequent complex temporal events which meant that these adventures of past Doctors were often occurring as a result of and simultaneous to the Eighth Doctor’s life. (PROSE: The Eight Doctors, Sometime Never..., Verdigris, et al.)

While the majority of sources indicated this reality was the same as the Doctor's reality in general, (PROSE: Seeing I, Millennium Shock, The Scarlet Empress, AUDIO: The Zygon Who Fell to Earth, Eyes of the Master, COMIC: Vortex Butterflies, et al.) some accounts claim this was distinct from the realities of other strands of the Doctor's life. (PROSE: The Eight Doctors, Unnatural History, Alien Bodies, Interference, Spiral Scratch, AUDIO: Zagreus) However, even the latter sources indicated this reality shared "eras and moments" with other prime realities (AUDIO: Zagreus) or layers of a constantly shifting history, (PROSE: Unnatural History, The Gallifrey Chronicles, The Eighth Doctor Part 2) with sources indicating overlap (PROSE: The Gallifrey Chronicles) and even merger with other universes. (PROSE: Interference)

Origins
Several accounts indicate this reality was created in the aftermath of the Eighth Doctor's regeneration. With the Doctor's biodata still fresh and unsettled, he unconsciously affected and changed any space-time he interacted with in his first days, "regenerating the past, present, and future". (PROSE: Unnatural History) left the Doctor a trap which erased his memories, and in that amnesiac state the Eighth Doctor was led by Rassilon's spirit into his own past to meet with and influence his seven prior incarnations at pivotal moments in their lives. Rassilon would admit that he'd used the Doctor to "make one or two small improvements in the patterns of history" (PROSE: The Eight Doctors) but the Book of Lies suggested the changes were sweeping, with Rassilon partnering with Faction Paradox to "fold back" the entirety of the Doctor's timeline to totally erase the history where the Seventh Doctor ended Pythia's curse. (PROSE: Unnatural History) The Doctor would speculate that Faction Paradox had changed history as far back as his birth. (PROSE: The Shadows of Avalon)

The Eighth Doctor once had a vision which told him that his universe was inside a bottle. (PROSE: Alien Bodies) Much as the Eighth Doctor's reality contained a bottle universe in which the Seventh Doctor had adventures, this bottled Seventh Doctor (PROSE: Interference) possessed a bottle universe in which the Eighth Doctor lived. (PROSE: Christmas on a Rational Planet) Another account indicated bottle universes were actually perfect looped recreations of reality, such that when Marnal examined the Eighth Doctor in a bottle universe the Doctor of Marnal's universe saw a gigantic version of Marnal watching him. (PROSE: The Gallifrey Chronicles)

Other accounts showed this reality as a natural possibility of the multiverse, being the prime universe (PROSE: Spiral Scratch, Wolfsbane, AUDIO: Zagreus) while also existing within the billion alternatives of anti-time. (AUDIO: Zagreus)

Additionally, this reality existed within the infinite sequence of palimpsest universes, being just the most recent iteration of reality. (PROSE: The Infinity Doctors, Unnatural History, The Gallifrey Chronicles)

This reality was also the timeline in which Antalin was destroyed instead of Skaro, (PROSE: War of the Daleks, Heart of TARDIS) which had several accounts of its creation. (PROSE: The Infinity Doctors, Unnatural History,  The Astounding Untold History of the Greatest Enemies of the Universe)

General outline
The circumstances of the Doctor's birth were indeed one aspect of history which differentiated this reality from others. Here, the Doctor was a half-human with a Time Lord father and a human mother. (PROSE: The Eight Doctors, Matrix, The Gallifrey Chronicles)

The first several Doctors had lives which shared the same general history as other prime realities, albeit with their standalone adventures as new "slices of alternity". Iris Wildthyme once noted that she and many other forces were "feeding back and looping round on the Doctor’s established past. Changing it for ever and giving him extra interesting times." (PROSE: Verdigris) For example, the Eighth Doctor's encounter with the Second Doctor notably led to the Second Doctor serving the Celestial Intervention Agency following his trial. (PROSE: Players, World Game)

The Sixth Doctor's life had several features which distinguished this reality from others. After his trial, the Sixth Doctor worked with the Eighth Doctor to ensure Flavia's re-election, leading to her still being the President of the High Council into the Eighth Doctor's lifetime. (PROSE: The Eight Doctors, Unnatural History) The Sixth Doctor ended travels with Evelyn Smythe by leaving her back on Earth. (PROSE: Instruments of Darkness) Later, the Sixth Doctor died as a result of defeating the multiversal threat of the lampreys. (PROSE: Spiral Scratch)

This reality had a sequence in the Seventh Doctor's life in which he travelled with a version of Ace whose birthname was "Dorothy Gale". (PROSE: Matrix) Due to further manipulations from the Eighth Doctor's era, Dorothy Gale was murdered and replaced with a nearly-identical version of Ace from another universe surnamed "McShane". (PROSE: Illegal Alien, Loving the Alien)

Following his role in this continuity's birth, the Eighth Doctor's early adventures were entwined with the an altered timeline of Sam Jones' life which was paradoxically created near the end of their travels together. (PROSE: Unnatural History) The universe's future devastated by the War in Heaven also affected the present, with the Doctor initially encountering it as a potential timeline somewhat averted by the Doctor's interaction with it. (PROSE: Alien Bodies) After being joined by Fitz Kreiner, (PROSE: The Taint) the Doctor tried to improve Sam's timeline but was disrupted by Faction Paradox and the War into creating an an infected version of his own past. (PROSE: Interference) which one account indicated was the timeline from which both Faction Paradox and the War originated. With the infected timeline competing with the uninfected timeline for reality, the Doctor was forced to destroy Gallifrey to ensure that the War never came to pass. (PROSE: The Ancestor Cell) The Doctor's reality thus continued into the post-War universe, which was still continuous with the adventures of his past incarnations despite the Time Lords being nearly extinct in the present. (PROSE: Endgame, The Gallifrey Chronicles, Sometime Never...) The Doctor and Fitz would be joined by Anji Kapoor as they faced issues of a universe without Time Lords, culminating in a multiverse collapse which temporarily left only one quantum possibility of the universe in existence. (PROSE: Time Zero, Timeless, et al.) After solving this issue, the Doctor, Fitz, and Trix MacMillan had several more adventures leading to the Doctor regaining his memories. (PROSE: The Gallifrey Chronicles, et al.)

Fate
As a bottle universe, the divisions between this reality and all other bottle universes were fated to shatter. (PROSE: Alien Bodies)

Observing the Eighth Doctor's timeline, Marnal noticed that three different timelines of the Doctor's ninth incarnation continued from this reality. (PROSE: The Gallifrey Chronicles)

One account indicated this version of the Eighth Doctor's life rejoined with the two other main parallel strands of his life as the Last Great Time War neared, such that all three existed in the Doctor's past from the perspective of the Post-Time War universe. (PROSE: The Eighth Doctor Part 2)

Relation to other realities
When Zagreus exposed the Positive-time universe Eighth Doctor to a billion alternate realities, the Doctor saw "an Earth upon which I have plucked out one of my own hearts", (AUDIO: Zagreus) resembling Sabbath Dei's removal of the Doctor's second heart. (PROSE: The Adventuress of Henrietta Street)

During his multiversal adventure, the Sixth Doctor saw a version of himself who travelled with a partly-cyberized Evelyn Smythe. (PROSE: Spiral Scratch)