“Fish people, come and see.”
How hard would it be to ever turn down the Doctor when he shows up and offers to take you someplace amazing? This is Clara’s life; juggling one awe-inspiring experience after another while going to work and trying to date a handsome teacher from her school. How long could someone keep up such a mixture of the amazing and the banal before their mind snaps?
Also, I’m not sure Peter Capaldi knows how to wink, did anyone else catch that?
The question of whether the Doctor can pass for a normal workaday guy is a fun way to start the episode's main story. He’s an ancient being who plays with time and space as if they were games on his phone, and he shares little to no frame of reference with human beings. For all we know he goes on adventures across dozens, if not hundreds, of years between picking up Clara for the next adventure. His mind is unknowable, sometimes even to himself, and that can be make it hard to "blend in" with others.
It’s funny to hear him say that he’s the alien in the school when he goes "deep undercover" as the new caretaker, but it’s also kind of a scary thought. If he’s there, it’s clear that something is likely about to go very wrong. Clara’s two worlds are about to unite, and the idea doesn’t make her feel very safe. She's used to going towards the danger, and she makes that decision willingly every time she steps in to the TARDIS. In this case the danger came to her, and it doesn't help that there are children around.
The story of the invading alien creatures, both the Doctor and the warlike entity that blows so much up in this hour, is an excuse for other things to happen though, and the solution to the problem is hand-waved away with some technobabble and a neat watch that grants the wearer invisibility. The monster of the week is there to help move the characters along their own path, and the writing is smart enough to realize this and focus on the three most important people: Clara, The Doctor, and Danny Pink.
There is real hurt and vulnerability in this episode, especially when The Doctor assumes Clara has fallen for someone who just so happens to look much like an earlier version of himself. She's in love with someone who used to be a soldier, however, and when she’s forced to explain the two relationships she says she loves one man, and the other is an alien.
Hearing it put so bluntly has to sting, even though the Doctor seems to treat Clara’s attention as something he’s entitled to whenever he feels a bit lonely. His little girl is growing up, and the heart he assumes he owned has wandered off into another direction, one of which he does not approve.
We see the face of someone dealing with a sort of jealous fear that is completely unfair, but still very real during this scene. Clara "elopes" with The Doctor every so often, according to Danny, but she doesn’t love him "in that way." The Doctor begins to understand that her life doesn't pause between their adventures, and in many ways that aspect of her is just as important as the one who travels through space and time. He doesn't take it well.
Clara spends the episode trapped between two people she never thought she would have to explain to each other. Her relationship with one person makes sense, the other relationship is complicated, and both of her significant others feel cheated on in some way. Neither of them force her to "choose," however, and by the end of the episode they've both adjusted their own view of her in some way, instead of forcing her to change how she lives her life.
It's a subtle, but rather impressive, difference that we rarely see in pop culture. Clara knows what she wants, and the "men" in her life are OK with adjusting their own point of view so she can have it.
The Doctor isn't a soldier, he's an officer
But these moments are earned, and this is also why the argument between Danny and the Doctor inside the TARDIS is such a dense scene. For one thing, Danny is inside the TARDIS, and that’s not a small thing on its own.
Secondly he stands his ground and clearly gets under the Doctor’s skin, and that also speaks to Danny’s resilience and spirit. While the Doctor’s petty dislike of soldiers may be rooted in personal bias of some kind, Danny gets the Time Lord’s number straight away.
The Doctor is not a soldier, you see, he’s an "officer." The way Danny zeroes in on the cold manner in which the Doctor uses other people and his seemingly constant sense of entitlement to their time and obedience is super-interesting, and clear the Doctor has a hard time keeping his temper in check as they verbally spar. They’re both being childish, but the Doctor comes off looking far worse in the exchange, and to his credit he seems to realize it by the end of the episode.
Why this episode is great
This season of Doctor Who has been well above average, with some effective episodes that move the entire series along on its often plodding, shuddering tracks. The monster isn't that important, the threat never feels that real, but every character we care about has to look at their lives, figure out what they want and they change how to they deal with each other to get it.
Peter Capaldi's ability to play up the arrogant and often unlikable side of the Doctor is one of the best things about his portrayal, and I understand why this isn't a popular choice from other actors who have carried the role. Who wants to be the petty, vindictive father figure?
But there are some great jokes in here, including the slight but interesting side-story with a young girl named Courtney Woods, a "disruptive influence" whose curiosity and forthright nature earns her a quick trip into space. We're reminded that the amazing is mundane to the Doctor, and he has to refresh his sense of wonder by seeing these things through the eyes of other people.
Who wants to be a petty father figure?
His note that "human beings have incredibly short lifespans. Frankly, you should all be in a constant state of panic," is also the sort of thought that has to be in the back of his head at all times, and it's funny when the writers and Capaldi allow his inner monologue to escape in this way.
This episode wasn't good because of the threat, it was interesting because everyone involved had something to lose, and it avoided a lot of the easy traps of what could have easily become a tired "love triangle" and instead created something much more interesting and resonant. More of this, please.