Doctor Who Series 12: 10 Things That Need To Happen In The Finale
2. One Of The Companions Dies
Well, they say three's a crowd.
It's been noted ever since the start of thirteen's time in the Tardis that three companions are too many. It's not something that's been done a great deal in Doctor Who, with only a couple of attempts at three supporting cast members in the 60s and one further go in the early 80s, with mixed results (poor Adric).
While this author has actually enjoyed the Team Tardis dynamic, it feels now like we're reaching the end of a couple of character arcs. Graham and Ryan have developed a great bond as grandfather and grandson, but we haven't really seen much more development this series on that. Ryan seems like a safe choice to stay, but the finale could be earth-shattering by killing off Graham, who could sacrifice himself to save Ryan.
Alternatively, Yaz is another contender. She's become slightly more agressive in recent episodes after questioning some of the Doctor's decisions and it's been speculated she could turn against her in the finale. It may be she also ends up sacrificing herself to try and redeem her character in the Doctor's eyes.