"To be honest, I did not know whether River [Song] would ever return to the show, but here she is, back with the Doctor for the Christmas special," says actress Alex Kingston, who returns for this year's Doctor Who Christmas Special, according to Variety.
The character, last seen as a data ghost dispersing before the Doctor jumped into his own timestream, has always had a timey-wimey existence in relation to the Doctor. With her story seemingly ended, it was unclear if her time-traveling existence would allow her run into Twelfth Doctor Peter Capaldi. On the matter of her return, head writer and executive producer Stephen Moffat says, "As ever, with the most complicated relationship in the universe, it's a matter of time …"
"Steven Moffat is on glittering form," adds Kingston. "Giving us an episode filled with humor and surprise guest castings. I met Peter for the first time at Monday's read-through, we had a laugh, and I am now excited and ready to start filming with him and the Doctor Who team. Christmas in September? Why not!"
The actress first appeared as River Song in Moffat's 2008 story, "Silence in the Library/Forest of the Dead," hinting that she was the Doctor's wife and knew his real name. She recurred throughout Matt Smith's time as the Doctor with the nature of their relationship coyly confirmed in 2011's "The Marriage of River Song" and referenced in 2012's "The Angels Take Manhattan."
Moffat, who became executive producer and chief architect of the program from its 2010 season onward, initially promised to tell the story of the Doctor and River "from beginning to end," but never revealed in what order that story would take shape.
The 2015 Doctor Who Christmas Special — as yet untitled — will air on BBC America in the US on December 25th.