: The Doctor refuses to take Ashildr with him in the TARDIS, believing that two immortals traveling together is a dangerous prospect.

: During the attempted execution of another thief, Sam Swift (Rufus Hound), Ashildr uses the artifact on him to open the portal. However, Leandro betrays her, revealing his intent to start an invasion of Earth.

: Realizing she still cares for humanity, Ashildr uses her second immortality medical kit to revive Sam Swift, which closes the portal and foils the invasion. Character Arcs and Themes

: Ashildr is secretly allied with a lion-like alien named Leandro . She plans to use the Eyes of Hades to open a portal to escape Earth, but the ritual requires a death to activate.