Clara being "monster'd" is one of the things fueling my latest crack theory: that Missy is actually a Clara echo gone wrong somehow, a distillation of Clara's bad side. (A Clara Valeyard? Clareyard? Or maybe just "Miss C?") Because Clara is fundamentally a balancing act—controlled yet impulsive, afraid yet bold, sincere yet constantly "on stage," sweet and nurturing yet ruthless when her people are in danger—and it seems to me that if Clara's traits went out of balance then you could get a very scary, messed up maybe-human being.

Well, that and I think that Clara versus Dark Clara Echo would be a hell of a cool thing and I'd like to have it on my TV.