Doctor Who: 5 Questions Raised By The Series 12 Finale
2. Is Tecteun Rassilon?
Tecteun was the Shobogan explorer who adopted the Timeless Child and brought her back to Gallifrey, andbecame the first Shobogan to regenerate after extracting the secret from the Timeless Child and testing it on herself. It isn't hard to believe she became an important person in early Time Lord society because of her scientific contributions, but did she become Rassilon?
Rassilon was credited with creating the majority of Time Lord society, but he was also obsessed with immortality. His search for ways of cheating death could easily be seen as an extension of Tecteun's drive to unlocking the secret of regeneration. Also, tampering with the Matrix's records of the Timeless Child by turning it into a story about an orphan boy in Ireland could have been Rassilon's attempt at hiding the truth from future generations of Time Lords.