Theory: What if Missy came back for the Christmas episode?
BBC
Everyone wants a companion to come back at Christmas. I have a better idea.
Everyone’s talking about which companion will show up at Christmas for the special. We know that Bill returns and that they asked Jenna Coleman.
It’s common for companions to return during the Christmas episode, and as this is Moffat’s last, I would expect nothing less than some surprises. We already have the First Doctor and Polly, Bill, and Mark Gatiss. As for Jenna Coleman being asked — there is still the rumor about her restaurant/TARDIS.
But if there’s anyone who deserves to be there it’s Missy. Missy took giant steps towards changing the Master and making him good. We learned a lot of information about how close the two were in the Academy. We learned about the adventures they wanted to go on as children. And of course, Missy died for the Doctor, which he doesn’t know.
Fans are (still) outraged that Missy died and never told the Doctor she was on his side the entire time. So, what if the fans got their wish?
Other surprises
It wouldn’t be the first time that fans were completely shocked by someone returning. For the 50th Anniversary, Tom Baker was smuggled into the BBC set to keep his cameo a secret. Karen Gillan also made a surprise cameo at Matt Smith’s regeneration.
Despite how often he said Clara or any of the funny memes about it, the person that mattered was Missy. It’s always been the Master for the Doctor. He’s always loved the Master in some way, whether as a friend, or more. We’ve always known, it was just more apparent this during his era, but especially this season.
For that, why shouldn’t Missy make a surprise visit when the Doctor is scared to regenerate? I can already hear her voice. “Get it together you silly sausage.” As he’s regenerating she can tell him she was on his side the entire time. And then imagine her reaction to the change to a woman!