 It was also Roberts'idea to bring back the Cybermen, because there were no other returning monsters in the series and he thought "there should be a sense of history about the Doctor's final battle to save Earth before he heads off to meet his death". He felt that this was consistent with the theme of "death and lingering darkness" that had run throughout the sixth series. Roberts wanted the audience to think that maybe Craig would really be converted. Moffat felt the "blowing the Cybermen up with love" conclusion was the Doctor Who version of a father bonding with his son. Roberts felt that the episode's depiction of the Cybermen put it on the "silly / terrifying axis" that was common in Doctor Who.
