Siobhan's character in Simon Stephens's play The Curious Incident of the Dog in the Night-Time does not differ greatly in terms of personality from the way she is presented in the novel. She is kindly, intuitive, and intelligent and is one of the few people in the world whom Christopher feels he can trust.

What is different in the play, however, is that Siobhan shares with Christopher the function of narrator. In the novel, Christopher is an unreliable narrator who often misreads the situation. In the play, Christopher's words are read by Siobhan, giving them some of the authority of her personality, if only through her judicious selection. Siobhan uses Christopher's own words to describe what is happening to him and what thoughts arise in his mind.

As the play opens, for instance, Mrs. Shears is hysterical when she discovers that her dog has been killed. Christopher then has a tense dialogue with the police officer, which ends in him lashing out and hitting the man. Throughout these emotional incidents, Siobhan is calmly giving the audience the story behind these events, making sense of them, and adding structure. This is the role she fulfils throughout the play, making her seem even more like the infallible voice of stability and sanity than she does in the book and also making her a more central character.