Vera is the most important character in "The Open Window." Saki needed someone who would prepare Framton Nuttel for a big shock when the three supposedly dead hunters returned at dusk. It couldn't be Mrs. Sappleton because it would be completely out of character for her to play such a trick. It had to be a mischievous child--but not too young because a young child couldn't bring it off convincingly. A boy or a girl? A girl would be best because a boy would probably be off hunting with the other males. She couldn't be too old, either. An older girl probably wouldn't have that same mischievous spirit. Fifteen was the best age for the author's purposes. He twice describes Vera as "self-possessed."
"My aunt will be down presently, Mr. Nuttel," said a very self-possessed young lady of fifteen; "in the meantime you must try and put up with me."
"Then you know practically nothing about my aunt?" pursued the self-possessed young lady.
Throughout the story Vera acts completely self-possessed--calm, cool, collected, poised, self-assured. Saki's purpose in emphasizing that Vera was "self-possessed" was to make it possible for her to terrify Framton at the end when the three hunters appear outside.
The child was staring out through the open window with dazed horror in her eyes.
Vera pretends to lose all her self possession, and the contrast, the sudden loss of her poise and self-assurance, convinces Framton that she is really looking at three ghosts. It seems possible that Vera gets a stronger reaction out of the nervous guest than she expected. She is perhaps a better actress than she realized. But she quickly recovers her habitual "self-possession" and makes up a weird tale to explain Framton's abrupt departure.
Vera is a fifteen-year-old girl who has a vivid intelligence and must do a lot of reading. She is mischievous, but she is not too much different from girls her age who like to play practical jokes on people. On the surface she is very polite and “self-possessed,” but underneath she has a secret sadistic streak which strangers and even close relatives would not suspect. No doubt she finds her life very boring at the age of fifteen, since the story is set in a time when women in general had little freedom and girls her age had even less. Judging from the characters described in Saki’s story, there is no one even approximately Vera’s age for her to relate to. She must spend a great deal of time by herself and probably indulges in all sorts of fantasies. She is a shrewd judge of people. She senses immediately that the visitor Framton Nuttel is a bundle of nerves and a hypochondriac. She foresees how he would react to a ghost story and invents one on the spot to watch his reaction and prvide herself with some welcome amusement. There is a similarity between this story and Washington Irving’s “The Legend of Sleepy Hollow.” For some reason, we don’t feel sorry for Nuttel, just as we don’t feel sorry for Ichabod Crane.