Final answer:
None of the characters mentioned (Peter, Mrs. Van Daan, Margo, or Anne) are explicitly described as 'mercurial' based on the provided information. The term describes a changeable and unpredictable nature, and while Anne seems to be a dynamic character, it is not clear if she is mercurial without further context.
Step-by-step explanation:
The term “mercurial” generally describes someone whose moods or behaviors are unpredictable and changeable, much like the Roman deity Mercury who was known for being swift and volatile. In literature, such a trait can bring depth to a character, making them complex and multi-dimensional.
However, based on the information provided, none of the characters listed - Peter, Mrs. Van Daan, Margo, or Anne - are explicitly described as “mercurial”. Instead, the brief character summaries suggest that Anne is a dynamic and possibly round character due to her perseverance and noticeable change.
Yet without a specific text to reference that contains these characters, it would not be accurate to definitively label any of them as “mercurial” based solely on this information.