Thirteenth Doctor

While she was no stranger to keeping secrets herself, the Thirteenth Doctor lived a life full of conspiracies and unearthed truths that left the Doctor unsure of her own identity. Though she managed to hide her insecurities behind a dynamic, curious, and endlessly caring persona, she would unleash her furies in short outbursts when in the heat of a stressful moment. However, these moments were few and far between, with the Doctor usually believing in hope, and compassion and providing help to anyone who needed it.

Her initial travels were relatively carefree, with her simply enjoying showing the universe to Graham O'Brien, Yaz Khan, and Ryan Sinclair, whom she called Team TARDIS and considered her "fam", after they chose to join her upon helping her recover her TARDIS following her losing it in her post-regenerative trauma.

These carefree travels came to an end, however, with the return of the Master, who teased a secret to the Doctor after he caused the second documented destruction of Gallifrey. As she processed her home being lost again, the Doctor encountered the Fugitive Doctor for the first time since her mind was wiped by the Division, a secretive organization founded in Gallifrey, cluing her into a secret history predating her alleged first incarnation. As her history began to unravel, the Doctor was finally told the truth by the Master when they reunited on the ravaged Gallifrey; the Doctor had once been the Timeless Child, found by Tecteun, the Other of the Founders of Gallifrey, who had experimented on the Child to uncover the secrets of regeneration before handing them over to the Division. Separating herself from her friends to protect them from the Master, the Doctor was imprisoned in a Judoon prison before she could fully digest what she had learned about the Timeless Child.

After she was rescued by Jack Harkness, the Doctor returned to her friends but arrived ten months after they last saw her, Graham and Ryan decided to continue with their lives on Earth, while Yaz decided to continue her adventures with the Doctor, having had trouble readjusting to a normal life after being fully immersed in the Doctor's world. Though she treated Yaz as her co-pilot, the Doctor kept her in the dark as she tried to find evidence of the Division to get answers regarding her stolen memories.

After finding a lead in the Lupar Karvanista, the Doctor and Yaz pursued him to Earth as he went to collect Dan Lewis, the human he was species-bonded to, in order to protect him from the Flux, a force that would take apart the very structure of the cosmos, bringing about the end of the universe. With old foes resurfacing from a past forgotten and remembered, the Doctor and Yaz, joined by Dan, forged alliances with new and old friends in order to bring an end to the Flux, which culminated in the Doctor finding Tecteun in the gap between universes, where she found her stolen memories within a Biodata module and learned that the Division, led by Tecteun, had unleashed the Flux to destroy the universe as they prepared to leave for "Universe Two". However, Tecteun was swiftly killed by the Ravagers and, as the Doctor's allies neutralized the Flux, they brought her before the personification of Time, who disintegrated them for their failure and allowed the Doctor to leave, but warned her of her looming fate.

Now knowing her end was nearing, had been ultimately forced to regenerate by the Master in a plot to take over her body, though Yaz was able to reverse the regeneration and bring the Doctor back. However, the Master, unable to accept defeat, fatally wounded the Doctor using the energy beam of a Qurunx, and she regenerated into her next incarnation after amicably parting ways with Yaz.

The Doctor is the timeless child from the planet of Gallifrey although her true planet and origins are unknown. Physically, she is 5 foot 6 inches with a slender but athletically toned body build, creamy pale skin tone, jaw length short blonde hair, and hazel brown colored eyes.