The End of Time
Moffat felt that it was important to bring something different to the return of Billie Piper, as she had returned as Rose Tyler in various cameo appearances throughout series 4, most prominently in "The Stolen Earth"/"Journey's End", in which she had a central role, and "The End of Time". This led to the development of the Moment, which had previously been referenced in "The End of Time". Piper agreed with Moffat's sentiments, despite loving the character of Rose.