Summary
One theory suggests that River Song may have appeared in Matt Smith's final Doctor Who episode, "The Time of The Doctor."
There is speculation about a possible connection between Tasha Lem, a character associated with the church of The Silence, and River Song due to their many similarities. However, it is unlikely that this theory is true because these similarities can be attributed to their shared experiences and Steven Moffat's comments indicate that they were not meant to be the same person.
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Despite The Doctor's farewell to his wife River Song in "The Name of the Doctor," speculation arises that she may have appeared in his final Doctor Who episode. In "The Time of The Doctor," Matt Smith's portrayal of The Doctor ends as he embarks on a mission to investigate a mysterious signal, ultimately revealing another rupture in time and space on Trenzalore—the planet where his demise is prophesied. Throughout the episode, The Doctor bravely defends Trenzalore against countless invasions, eventually receiving a new regeneration cycle that saves him from certain death. Many viewers had hoped for a reunion between The Doctor and River Song in this episode, only to be disappointed by her absence. However, an intriguing theory suggests that River may have indeed been present in the narrative, assuming an entirely different identity.
Tasha Lem Could Be Another Incarnation Of River Song
River Song had frequent encounters with the Eleventh Doctor in Doctor Who, surpassing any other incarnations thus far. Their romance developed gradually throughout the seasons, making it disappointing when River was not included in Smith's final story as The Doctor. However, "The Time of The Doctor" introduced Tasha Lem, a character who played a significant role and surprisingly shared many similarities with River Song. Tasha Lem was heavily involved with the church of The Silence and also displayed flirtatious behavior towards The Doctor, hinting at a potential romantic history.
In Doctor Who, it was revealed that River Song possessed the ability to regenerate like a Time Lord because she was conceived in the Time Vortex. However, she seemingly relinquished this ability to save The Doctor's life in "Let's Kill Hitler." Therefore, it can be deduced that Tasha Lem is a version of River Song from the past, predating even her previous incarnation as Mels. This raises intriguing questions about the relationship between Tasha and River, including why Tasha would recruit a future version of herself to follow the commands of The Silence.
Why This Theory Probably Isn’t True
The idea that Tasha Lem is a previous incarnation of River Song lacks coherence. Their similarities can be attributed to their shared power as women within the church of The Silence, suggesting that they have interacted and possibly influenced each other's personalities. Steven Moffat has acknowledged that Tasha Lem was unintentionally written too similarly to River Song, reinforcing the notion that they are separate characters. Considering The Doctor's astuteness, it seems unlikely that he would not have recognized this connection earlier.