Warning: Minor Spoilers from the His Dark Materials books ahead.
His Dark Materials' second episode, 'The Idea Of The North', continues to make some big changes from the book series that inspired it - including one major difference to the relationship between Mrs Coulter (Ruth Wilson) and her daemon. The latest installment of His Dark Materials focuses largely on the burgeoning relationship between Mrs Coulter and Lyra (Dafne Keen), as Lyra starts to learn how to behave like a lady. At first, Lyra is amenable to this, awed by Mrs Coulter's position with the Royal Arctic Institute and the people that she knows. However, as time goes on, Lyra becomes increasingly suspicious... with good reason.
At night, as Lyra and Pantalaimon are in bed, they hear something in the walls. As Lyra becomes increasingly suspicious, she sneaks out of bed to investigate and sees Mrs Coulter's daemon sitting alone in the office. She realizes that the monkey has been using the air ducts to wander around the apartment, far from Mrs Coulter, something Lyra questions her about.
Although she obviously doesn't say herself, this means that Mrs Coulter and her daemon are not like normal humans: they have been severed. In the world of His Dark Materials, it is only possible for humans to be a short distance away from their daemons at any point. From Lyra's reactions when Pan is being hurt, and from her discussions with Pan, it is clear that if daemons move too far from their humans, it is physically painful. They also feel some of the pain that their daemons feel. However, in this episode, Mrs Coulter is seen hitting her daemon, yet feeling no pain. It's also obvious that her daemon can be far from her, without any issue. This prompts Lyra to ask Pan: "What is she?"
While it has not yet been revealed in the series, book readers will know what is happening here. In the His Dark Materials books, it is possible for a person to be 'severed', meaning that the connection between themselves and their daemon is cut. This keeps a level of connection, but turns the daemon into a 'perfect pet', rather than a true other half. This is still extremely rare, but is being investigated by the Magisterium, and Mrs Coulter is involved.
However, in the books, Mrs. Coulter's relationship with her daemon is an utterly normal one, and she is not severed, so this is a change made for the show. While the book series sees Lyra meet severed adults, Mrs Coulter is not one of them. In fact, when the monkey spies on Lyra in the books, Mrs Coulter is seen to be visibly uncomfortable at having her daemon even slightly further away from her, and his fur is shown to reflect her emotions. This means that the two are still connected.
The decision to make this change, then, is an interesting one. It is definitely helpful in making Mrs. Coulter seem to be more of an inhuman villain figure, and explains how Lyra becomes so disenchanted with her - for reasons that make more sense than simple teenage-girl attitude. It also starts to lay the groundwork for some of the bigger mysteries in the series, which helps keep the series moving at a good pace, without giving too much away. Finally, this means that Mrs Coulter may be more powerful than her literary counterpart in some ways... but should His Dark Materials continue to the events of The Amber Spyglass, it may affect her abilities to use something called an 'Intention Craft' - however, fans will just have to wait and see how the show chooses to play this one out.