In "The Open Window", Vera, the young girl who greet Framton Nuttel at the door, is a pathological liar.  Since she lives with her aunt and uncle, it can be assumed that she is an orphan being cared for my relatives.  Also, since she is a teenager, it can be assumed that she likes the attention she gets when making up "romances" on the spot.  When Framton Nuttel arrives, it is with a letter of introduction to Mrs. Sappleton who was going to allow the young man to stay at the house while recovering from a nervous breakdown.  For wahtever reason (probably jealousy that he might take attention away from her), Vera tells a wild tale about how her uncles went hunting one day and never returned.  She claims that her aunt has gone mad and has never given up hope that her husband and the others will return, and so she keeps the window open for them (it's more like a French door with large windows than a common window).  Vera scares Framton Nuttel so much with her lies that when the men DO return (they actually had been out hunting that morning), he runs as if he'd seen ghosts, leaving the Sappletons to wonder what was wrong with him.  Vera once again lies and says that Nuttel had just finished telling her a story of how he was once attacked by a ferocious dog, and the sight of their hunting dog terrified him.  The family believes her tale, putting Vera in the position she likes: as the center of attention with all the answers.