The Warrior

The Warrior was the name used by the fifth incarnation of the Doctor from an alternate universe where the Fourth Doctor fulfilled his mission to alter the creation of the Daleks. (AUDIO: Dust Devil)

He was also referred to as "the Doctor that Was" by the Unified Skaroan Alliance, (AUDIO: Aftershocks) and was considered by the White Guardian to be a "deviant" and "aberration" of the timeline that should never have been. (AUDIO: The Key To Key To Time)

Regeneration
In a version of history, Sarah Jane Smith successfully convinced the Fourth Doctor to go through with destroying the Daleks. After doing so, they and Harry Sullivan tried to escape Skaro with the Time Ring, but both Sarah and Harry were killed by a prototype Dalek, which also shot the Doctor. However, the Doctor was extracted by Narvin just before the blast could fully kill him. Still slowly dying, Narvin provided the Doctor with the last Elixir of Life of the now destroyed Sisterhood of Karn, triggering the Fourth Doctor's regeneration into the Warrior.

As the results of the Fourth Doctor's decision rippled through time, the Warrior entered the Time War. He sent two temporal bullets to kill alternate version of the Sixth Doctor and Peri Brown, who had been deemed temporal "aberrations". (AUDIO: Dust Devil) Throughout the Time War, the Warrior fought on many worlds, sometimes alongside the Master. (AUDIO: Aftershocks) On one occasion, the Warrior visited a planet under Dalek bombardment and promised he would destroy the entirety of the Dalek race. (WC: Doctor Who Unbound - Doctor of War: Genesis)

However, due to the Time Ring being left on Skaro, the Unified Skaroan Alliance, comprised of the allied Kaleds, Thals, and Daleks, gained control over the Time Vortex and all of time, retroactively conquering Gallifrey and the CIA, effectively winning the war. With the CIA, the Alliance placed the Warrior on trial for genocide, but with the help of the Master he trapped the timeline where the Alliance conquered time within a Carrisent Particum. Upon first regenerating, the Warrior had visions of this timeline. He was unsure if sealing it avoided it or if it was still to come in his future. (AUDIO: Aftershocks)

Trying to end the War
After many years in the Time War, the Warrior eventually became Lord President. He spent much of his time consulting the Matrix for answers on how to end the war, and became close to his assistant Borusa. On Gallifrey, the CIA established the Difference Office, a branch devoted to studying and preventing paradoxes, particularly those caused by guilt-ridden Time Lords attempting to kill their past selves. The Warrior ordered these Time Lords to be executed. One day, an individual appearing like the Warrior but claiming to be the Doctor gathered the Shobogans and proceeded to attempt to depose the Warrior as President. The Warrior revealed this to be an android created by the Kraal Styggron, who forced Borusa to induct him as President.

Styggron captured Romana and took her to inject her with a virus that would kill all the Time Lords. The Warrior used the Relics of Rassilon to atomise the Kraal fleet from Oseidon, and replaced Romana with an android duplicate, stopping the virus and allowing the Warrior to find Styggron's location. Styggron revealed to the Warrior he was actually working for the Alliance and the Daleks, and offered to ally with the Time Lords to end the war. However, the Warrior chose to kill him as vengeance for the death of Borusa's lover Zorcha. (AUDIO: The Difference Office)

Eventually moving on from his position as Lord President, the Warrior sought other options for ending the War. He essentially supervised the Master's plan to use the supercomputer Xoanon to create a new race that would give the Time Lords an advantage in the War, maintaining an approach of plausible deniability so that he would not know the full extent of what the Master did. (AUDIO: Who Am I?) The Warrior and the Master subsequently tried to track down an apparent temporal weapon on the planet Marinus, but when the Warrior established that this was the result of a temporal anomaly caused by the TARDIS's initial materialisation, he left the planet to be destroyed by the subsequent temporal anomalies, also leaving the Master behind as he concluded that his former friend could no longer help him. (AUDIO: Time Killers)

Ending the War
Eventually, old and resigned to the apparent impossibility of ending the Time War, the Warrior was contacted by the last of the Guardians, who directed him to find the Key to Time in the company of Davros. It had been so long since the first trip to Skaro that the Warrior did not initially recognise Davros, and Davros obviously failed to recognise the Warrior, but each acknowledged that they were essentially forced together as they were clearly on the side of the Time Lords and the Daleks respectively. The two were able to assemble six segments of the Key, but the temporal distortions of the current universe were so significant that the Warrior and Davros essentially acquired segments of the Key from different realities, making it impossible to assemble the Key themselves.

The Guardian was able to help them put the Key together, but it was apparently destroyed by another group who sought to end the War by destroying the rest of existence. The President of this group attempted to recruit the Warrior to their side, but the Warrior rejected this offer in favour of comforting Davros, having formed a tentative understanding of Davros during their time together and choosing to essentially be a Doctor once again. The Guardian returned and revealed that the Warrior and Davros actually personified the power of the Key within themselves: the physical form of the Key was unimportant as the seekers had absorbed its power into themselves. Recognising that they were the key players in the Time War as the ones responsible for the whole conflict, with Davros instigating the war by creating the Daleks while the Warrior would end it across virtually all realities, the Warrior and Davros used the power to take themselves out of time completely.

While Davros found himself caught in a loop where a Dalek would execute him, the Warrior was apparently able to reset his timeline so that the Doctor never touched the original wires together, transferring a part of himself back to his original visit to Skaro and resuming his travels with Sarah and Harry even as another part of his consciousness remained trapped outside time. (AUDIO: The Key To Key To Time)

Personality
Like N-Space's War Doctor, the Warrior had abandoned the name "Doctor". (AUDIO: Aftershocks) He did not have any reservations to kill, and, similarly to the Sixth Doctor, he could be rather brusque when provoked. He carried a strong hatred against the Daleks. (AUDIO: Dust Devil, Aftershocks) After many years in the Time War, the Warrior grew weary but nevertheless remained devoted. (AUDIO: The Difference Office)

Appearance
The Warrior resembled N-Space's Sixth Doctor, but his attire resembled his N-Space counterpart's war incarnation. The Warrior wore a brown leather trenchcoat and a double breasted waistcoat of dark green-brown moleskin with 10 brass buttons and a fob chain attached to it. (AUDIO: Aftershocks) For neckwear, the Warrior wore a scarf knitted in a burgundy and ivory herringbone pattern. (AUDIO: The Difference Office)

Behind the scenes
As shown on the trailer of Genesis, the Warrior's TARDIS' interior resembled that of the Fifth, Sixth and Seventh Doctor's console rooms, but in disrepair and beginning to collapse in on itself.