The end of Flatline saw a twist in Missy's focus, with her revealed to be monitoring Clara to some degree. Calling her "my Clara" and stating she has "chosen well", this was the first official inkling that the Doctor's current assistant will play a part in her plan. What that plan is will unravel in the next two episodes, but for now we can think about what exactly she's chosen. There's an infinite number of Clara's out there, saving the Doctor at various points in his past, meaning Missy could have spent a lot of time looking for the genuine (or perhaps just what we think is genuine) version. Has she chosen a Clara and now realising it's one who's important to the Doctor? Interestingly, this season has seen Clara and the Doctor clash over ideals more often, with the ethics of the Time Lord repeatedly called into question. Flatline saw Clara take charge, filling the leadership role, so it could always be this emergent trait that has Missy excited; she's distinguishing herself from other companions. Conclusion: Clara clearly plays a part in Missy's plans. Whether it's in reference to her multiple selves, her role as a companion or as an increasingly important representative of humanity is still uncertain. We're going to take a guess and say it's the first one.
