The Dominie

The Professor, also known as the Dominie, (PROSE: The Choice) was an individual who travelled in space and time with Alice, nicknamed "Ace", in the Cosmos. Despite his human appearance, he claimed that his biology was not human and that he was centuries old. (PROSE: Republica) His timeline and the universe around him were constantly being rewritten, something he was generally aware of. (PROSE: Republica, The Choice)

Origins
The Dominie described himself as a fourth-dimensional being. Because of this, he remembered several different pasts and futures, as well as multiple alternative presents, including ones where he travelled with "archaeologists and androids". (PROSE: The Choice)

Travels with the Mistress
In some past life which may not have corresponded exactly to his specific timeline, the Dominie remembered knowing a version of the Mistress, whom he greatly admired. He kept a picture of her in a silver locket. (PROSE: The Choice)

Indeed, at some point before her adventures in Ecto-Space, the Mistress remembered travelling with a man whom she trusted absolutely. She would later state that "I was ready to give up my life for him. I thought it would last forever. That we would go on forever, as we were". Her travels with him and K9 apparently involved a lot of "recky". (AUDIO: The Choice) On one occasion, the Mistress and her mentor took a holiday in 19th century Imperial Russia where they learnt ballet dancing from Charles Didelot and thwarted the plans of warmongering interdimensional beings known as the Iele.

When she travelled with him, the Mistress's mentor had the appearance of a "tall man" with "wild hair", wearing an oversized coat. This appearance would later be borrowed by the gestalt ghosts of Lukor's victims when they wished to communicate with her without alarming her. (PROSE: The Choice)

The Mistress eventually left her mentor; unable to return to her original home due to the way her travels with him had changed her, she felt she had no choice but to move on to Ecto-Space in the company of a K9 unit. While delirious due to a fever, she seemingly repeated words from their separation: "But that's just it. Time to choose. I have to be my own--". (AUDIO: The Choice) These words echoed those of the Time Lady Romana when she split up with the Fourth Doctor and moved to E-Space with K9 Mark II: "But it is, isn't it? A moment to choose. I've got to be my own Romana". (TV: Warriors' Gate)

According to B.E.S., the legends about the Mistress mentioned that she once had a mentor of sorts who showed her "the wonders of her old universe" until "one day, she decided to go at it alone", protecting Ecto-Space ever since. (AUDIO: B.E.S. Begins)

Travels with Alice
In his version of reality, the Dominie travelled with Alice, (PROSE: The Choice) who usually went by the name of Ace, in the Cosmos. At this point, he usually went by "the Professor".

The Professor and Ace once visited 1990s England only to discover that history had been dramatically altered by an escaped Ithacan criminal known as LeCompte. They discovered the truth about LeCompte's origins and plan to steer Earth's technological development so that he could direct its military forces at his homeworld in revenge for his exile and, realising that the wormhole back to LeCompte's homeworld was also a time rift, the Professor tricked him by allowing him to fire the war rocket Behemoth through the wormhole. This lay waste to the past version of Ithaca, killing LeCompte's past self and consequently cancelling out his alterations to the timeline. Ace was horrified at the Professor destroying this version of history, aberrant as it was. (PROSE: Republica)

The two later landed at a top-secret British research base in Greenland during World War II, where they helped defeat voracious insectoid monsters, (AUDIO: Island of Lost Souls) and on the holiday planet Millanno, where they uncovered the secrets of the darker half of the Isle of Prosperity. (AUDIO: Prosperity Island)

Separation and renewed travels
At some point, Ace became separated from the Dominie and was cared for in an unfamiliar place by Dorsai. (AUDIO: The Left Hand of Darkness) The Dominie picked up a new companion, Nadia. (AUDIO: The Other Side)

The Dominie and Ace were reunited and travelled to the Vespertine Lodge in 2036 in search of the legendary Point of Stillness. The pair discovered that the strange time bubble effect at the Point was actually caused by a time prohibitor, a "banned party trick". (AUDIO: Guests for the Night)

In a slightly different version of history, the Professor and Ace visited a temple built on a "weak point in the linear universe", whose clerics were instantly aware that many timelines overlapped over Ace. Neither of them remembered bringing down the Protectorate, which came as a surprise to the Professor as he usually knew when his timeline was being rewritten. Ace asked if a mysterious "him" they had defeated in the past "after all this timeline rubbish" was to blame, while the Professor was more evasive, stating that there were others who could "meddle with things". They had a heart-to-heart about the moral weight of people from aberrant timelines, with the Professor reaffirming that "everyone mattered" even if they were native to unstable timelines. (PROSE: Republica)

Adventures alone
Travelling alone under the name of "the Dominie", he made his way to Ecto-Space. He discovered the horrors that had taken place on Jokastarna under Emperor Lukor's regime, and which had been exposed by his old associate the Mistress. He was unable to alter history to prevent the genocide of the caveys, but decided to help steer the destiny of the post-Lukor, parliamentary Jokastarna. He knew that a lecture by a surviving cavey, Tris'Tean, given at the University of Arintanqex would be decisive in Ecto-Space's other residents condemning Lukor's old regime once and for all. He knew that a surviving Lukor loyalist, Duke Erukin, would attempt to assassinate Tris'Tean at the lecture. After dealing with other Lukor loyalists a week after the lecture, he went back in time to before the lecture and met with Tris'Tean, warning him about the assassination attempt and telling him how to avert it. (PROSE: The Choice)

Eventually, the Dominie, now named Dominic Perkins, found himself living a settled domestic life in the town of Suburbton, along with his adoring wife June and their layabout son Kevin. Dominic worked at a local office for Sir, who sometimes came over for dinner. During one visit, Dominic began to be plagued by visions and memories of heroic adventures he had once had across time and space. He realised that his current life was filled with generic sitcom conventions, such as a disembodied laughter produced by a hidden CannedLaughterTron, and that the world outside their house was an empty void.

Dominic persuaded Sir to commission a prototype timeship based on his vague recollection of travelling in a blue box. As Dominic challenged the reality of Suburbton, June finally admitted that she was the one who had created this world and trapped him. She offered to change her form and reshape her world however he wished, but he insisted that his love was for the universe, not for any one person. June then begged Dominic to take him with her as a companion, insisting that he could never really know whether his science-fiction adventures were any more real than their married domestic life. Dominic admitted that she was right, but rejected her love and left for his ship. (AUDIO: Punchline)

Physical appearance
The Dominie appeared as "a little man in a dark, buttoned-up yellow coat, wearing a matching tartan scarf". (PROSE: The Choice) During his travels with Ace in an alternative England, he wore a "slouchy brown coat" but also had the tartan scarf. He had grey eyes (PROSE: Republica) and brown hair streaked with grey. (PROSE: The Choice)

When he visited Vespertine Lodge, he wore a black pinstripe suite with a red ribbon pinned on its breast, over a blue shirt, with a patterned tie. (AUDIO: Guests for the Night)

Behind the scenes
The Professor was one of the two titular protagonists of The Time Travellers, one of the first subseries of BBV Productions' Audio Adventures in Time & Space. Portrayed by Sylvester McCoy, he was strongly implied to be the Seventh Doctor. Various people involved, including McCoy, felt they were too blatant a copy of Doctor Who and the BBC would send a legal warning over it. The second series of audios would rename him the Dominie, a suggestion by McCoy himself (Scottish for "teacher or master", according to Nigel Fairs). (REF: Downtime – The Lost Years of Doctor Who)

The 2021 novelisation of Republica (the first Time Travellers story) tied itself to the licensed DWU via the licensed usage of Doctor X. It notably presented an alternative possibility for the Professor's identity instead of the BBC Doctor: near the end of the novelisation, the Professor says they need to get "back to the Cosmos", the spacecraft of Doctor Omega. However, the implication is that the framing story seen in the Prologue and Epilogue features versions of Ace and the Professor from another version of their timeline, with the window where they were "the Professor" and "Alice" travelling in the "Cosmos" being the result of alterations to time by an unknown party. More specifically, it could be interpreted as taking place in the timeframe of the Virgin New Adventures, at some point after No Future, with the "real" Seventh Doctor and Ace: when she learns that she and the Professor had to deal with a rewritten version of Earth that ultimately had to be destroyed to restore the normal course of history, Ace thought that they'd already dealt with an unspecified "him" after "all this timeline rubbish", and the Doctor's reply states that there are others who "meddler". This appears to refer to their encounter with the Meddling Monk and the Silurian Earth incident.

"That's the trouble with being a fourth-dimensional being, too many universes and timelines to keep track of. One minute I’m traveling with archaeologists and androids, the next I’m traveling with a woman called Alice."

- Epilogue to The Choice

2022's novelisation of The Choice added an epilogue featuring "the Dominie". There, he casually mentioned that as a fourth-dimensional being, he was aware of multiple overlapping versions of his life, which came with different names. He contrasts the version of himself who travels with "a woman called Alice" (the "BBV Ace") with the version who travels with "archaeologists and androids", alluding to the Seventh Doctor's Virgin New Adventures companion Bernice Summerfield and his Death Comes to Time companion Antimony. He also mentioned knowing a version of the Mistress in the past (the Mistress being an analogue to the TV Doctor's Romana II in much the same way the Dominie is an analogue of the Seventh Doctor).