Teamwork is one of Doctor Who’s biggest themes. So why do the Doctor and his companion so often face danger apart?

Bill and the Doctor travel together, laugh together, uncover mysteries together, and solve terrible dilemmas together. It’s always their different strengths that ultimately make their mission succeed. Last week’s Doctor Who episode “The Eaters of Light” was a great example of how the Doctor and his companion function at their best.

If we look at “The Eaters of Light,” we have a perfect example of a formula that’s been used countless times on Doctor Who, and which is still one of the most successful storytelling methods on the show. The Doctor and Bill arrive at a location with no idea of what’s actually going on, and set off in different directions, following different interests. In Bill’s case, this makes her end up trapped in a hole with a legion of Roman soldiers, while in the Doctor’s case, he and Nardole are captured by a particularly angry Scottish tribe.

This results in a great part of the episode taking place with the main characters separated from each other: in this case, for a few days. Each one has to help their newfound companions discover a solution to the problem they have, eventually find their way back to each other, and somehow save the world together. It also results in what is probably the most satisfying type of episodes on Doctor Who: the kind where we see both the Doctor and his companion shine in their own ways, and showcase what makes us love them so much.

There are many other memorable episodes where we see amazing teamwork on Doctor Who: The Empty Child, in which, while the Doctor pursues the mystery of the ghostly boy, Rose meets Jack Harkness and solves part of the mystery on her own; Martha’s amazing journey keeping the memory of the Doctor alive in Last of the Time Lords; Donna and the Doctor’s hilarious reunion in Partners in Crime as they discover each other working to take down the same enemy; and more recently last season’s Under the Lake/Before the Flood, where the Doctor and Clara are separated in a doomed underwater base.

Teamwork is of course a key element to any cast of characters of any show, but in Doctor Who it seems to hold particular weight. In a show where the environment and secondary characters change so frequently, what really keeps us rooted in the story is the ease and love with which the Doctor and his companion work together.

The Doctor is a good person because he has someone to balance out his almost-absolute power; because he has someone to question his decisions and help him see things from a more human (and perhaps less cynical) point of view. Like all companions before her, Bill has definitely stepped up to this role, questioning the Doctor’s often callous approach to society, demanding that he see even the truths he doesn’t want to see, and pushing him to do better, every time.

But this is only half of what makes a companion a good companion. It’s not, in the end, what makes the Doctor and Bill function so well as a team… or any of the others, for that matter. What makes the show so enjoyable to watch, especially when it comes to episodes like “The Eaters of Light,” is seeing the values that unite the two main characters: values so firm and so secure, that they keep the Doctor and Bill united, even when they haven’t seen each other for days — or in the case of some companions, such as Martha, for years.

It’s when they function as a team even when they’re apart that you know the companion is really able to hold his or her own.

In “The Eaters of Light,” this was particularly obvious by the different approaches the Doctor and Bill had towards their respective captors. While the Doctor is much sterner in his attitude toward the Picts, Bill persuades the Romans to follow her in a friendlier way. In the end, both approaches are necessary for each party, and when they convene, it becomes clear that both have made them realize that they need to put aside their differences and work together.

It’s a clear case of excellent teamwork, when two people with vastly different abilities, united by a common set of values, can make the impossible happen. And both in Doctor Who and in the real world, that’s a beautiful thing to see.

What’s your favorite teamwork episode on ‘Doctor Who’?