The amazing "Doctor Who" Christmas special. "River Song" got herself trending on Twitter for the big news, which has fans excited -- and curious. How is this going to work?

The time-traveling River Song is married to the Doctor and has appeared in 15 episodes since 2008, but this will be her first interaction with Peter Capaldi's Doctor. It's also the first time viewers will see her since she appeared to die.

"To be honest, I did not know whether River would ever return to the show, but here she is, back with the Doctor for the Christmas special," Kingston said (via Variety). "Steven Moffat is on glittering form, 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!" Executive producer Steven Moffat said, "The last time the Doctor saw her she was a ghost. The first time he met her, she died. So how can he be seeing her again? As ever, with the most complicated relationship in the universe, it's a matter of time ..."

A matter of time... RadioTimes listed a bunch of potential ways it would make sense for River to return, with the first being "It's an earlier version of River." They offer an extended argument for why that's the case, and it does seem most likely.

Do you agree that viewers will see an earlier version of River? If not, what's your theory? "Doctor Who" begins its new run on September 19 on BBC America.

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