Since Clara’s initial appearance in Asylum of the Daleks, it was clear that something was going to be different about this new companion. Her reappearance in The Snowmen confirmed this suspicion, sparking jokes about Soufflé Girl giving Rory a run for his money in the most-deaths category. This isn’t the first time Moffat’s introduced a character with a mysterious past; his most famous example is River Song. But despite her divisive nature, I feel her plot arc succeed in in a way Clara’s has not.
First of all, River Song’s role as a reoccurring character allowed writers to space out her episodes, instead of continuously having to incorporate a mysterious background. Between River’s introduction in season four and the reveal of her identity in season six were 30 episodes*, of which she appeared in nine (all but one were two-parters). In comparison, Clara’s introduction and reveal have been compressed into one season, appearing (in some form) in all but four episodes. While the compressed nature of this arc could be justified by Clara’s role as a companion, it creates a cramped feeling. While River’s arc stretched longer, it was interspersed with other plots, such as the cracks in time, and didn’t become the key arc until season six.
Secondly, each story of River’s arc adds something new to the viewer’s understanding of her. At the Library, we are as befuddled as the Doctor, knowing only that she’s met him before. The episode ends with the first significant clue: she knows his name.
In Time of Angels/Flesh and Stone, viewers learn slightly more. She can fly the TARDIS, having had lessons from “the very best. Shame (the Doctor) was busy that day.” More ominously, she is in prison for killing “a good man. The best man she’d ever known.” Though the second part isn’t part of her initial identity, it remains in play to the end of season six.
The Pandorica Opens and The Big Bang are more plot-driven, though we do see her leave messages for the Doctor (with the implication she does so regularly) and make a Dalek beg for mercy. The latter heightens our curiosity---what could she have done to inspire that level of dread? The nature of her connection to the Doctor is teased as well.
Are you married, River?Yes.Hang on, did you think I was asking you to marry me or asking if you were married?Yes.But was that yes or yes?Yes.
Her reappearance in the season six premiere focused more on her relationships with the Ponds and the Doctor, though viewers learn that the first time the Doctor met her, as a child, he already knew “everything about her.” Only in AGMGTW do we learn her true identity, tying together the main themes of season six: Amy’s pregnancy, the regenerating child, and River’s background.
While it is still possible that Name of the Doctor will pull off a similar connection, the lack of visible clues leaves me concerned that Clara’s identity, whatever it is, will seem random, rather than purposeful. Despite the plot twist of Oswin’s true form in Asylum and the confirmation of a connection in The Snowmen, very little has been revealed since then. In fact, all indications, from her childhood background to the conclusions of the empathic psychic, suggest that she’s a perfectly normal girl who just happens to have two duplicates with a similar interest in soufflés and identical tastes in last words.
*two-parters counted as two episodes