Academic Athlete: Beth describes herself as smart in her opening narration, and a couple of paragraphs later, the narrative calls her and the bully she's fighting with "athletes". She does turn out to be good at sports and equally good in the classroom, impressing Watson and human!Doctor. Badass Bookworm in the making.
Adult Fear: So... two kids are murdered by possession, just as in the original... and then you have those same two kids with guns on a high school campus. (Note that "Human Nature"/"Family of Blood" had nothing to do with American school issues, and that this story was based on the original two-parter.)
All Up to You: It all boils down to one teenage girl with a soul in a fob watch.
Badass Boast: "I've seen the Doctor. I've seen you with him, you and Dr. Watson. The three of you... You're like... fire... and ice... and everything terrible and wonderful about light and darkness. And the Doctor... He's ancient — I've seen that. Burning at the centre of time. Able to see the turn of the universe."
Bavarian Fire Drill: Messrs. Vernet, Walker, and Smith are just three teachers from the UK, nothing to worry about...
Break the Cutie: You thought that removing the romance from the story would make it less heartrending? You would be wrong. Oh, so wrong...
Changed My Jumper: Played with. Holmes and Watson are undercover, and Holmes is the consummate professional at undercover work. They're just two British gents who happen to be high school teachers... except that Beth doesn't buy Holmes's unchanged accent.
Cool Teacher: So... John H. Watson, M.D. is an English teacher, and Sherlock Holmes is a fencing instructor. Oh yes.
Creepy Child: Daughter of Mine, who possesses the body of Beth's best friend.
Jumped at the Call/The Call Put Me On Hold: Beth is all set for adventure (it's in her blood), and the Doctor tells her "not yet". She'll have to wait two more years in her own timeline, which is a couple of months for the Doctor and Holmes and over a year for Watson.
Karmic Death: Son of Mine is the one member of the family who shoots someone onscreen. Watson ends up having to shoot him to keep him from taking the watch from Beth.
Mid-Season Twist: This isn't the first time we've had a heroine in the season, but it is the first time that an episode happens largely from said heroine's POV. That being said, this episode is the one that's the game-changer, because it introduces Beth who, two episodes later, becomes one of the main characters.