Keira Sanstrom was a Time Agent in training.
Biography
After Keira was sent to Calandra as part of her training, she eventually got bored and decided to dismantle her vortex manipulator to remove its limitations, but did not know how to put it back together afterwards. Stranded, she interfered with Calandra's technological development in order to get herself a means of transportation to Earth. Having read files on the Doctor, she hoped to track him down so that he could assist her.
Eventually, she tracked him down to St Luke's University, dismantled Nardole and kidnapped him, then in his twelfth incarnation, in order to get her to Calandra again. (AUDIO: Flight to Calandra [+]Loading...["Flight to Calandra (audio story)"])
Keira was entrusted with guarding the Paradox Armoury. At the entrance to the Armoury, after sending the Keystone "far away", (AUDIO: You Only Die Twice [+]Loading...["You Only Die Twice (audio story)"]) she was apparently murdered by a Discordia who took on her identity and began travelling with the Twelfth Doctor in the TARDIS. (AUDIO: Never the End Is [+]Loading...["Never the End Is (audio story)"])