how do we know that Mrs.Whatsit is odd - but friendly?

Mrs. Whatsit is one of the three ladies who help Meg, Charles Wallace, and Calvin travel through time to fight the Dark Thing and rescue Meg's father. At the beginning of the book, so steals sheets from a townsperson which causes some to believe her to be a tramp. She, however, is a clumsy and, often silly, lady who befriends Charles Wallace and offers moments of comic relief on their journey.

The reader soon learns that Mrs. Whatsit, in a previous life, was actually a star. She lost her star life doing battle with the Dark Thing; and though she managed to wound the Dark Thing, she herself lost her ability to shine in the sky.

IDK