Who is Mary Crawford?

Mary Crawford is Henry's sister, and Mary falls in love with Edmund Bertram. She is calculating about her affections from the beginning, considering which of the two Bertram sons would make a better match. She initially thinks that Tom would make a better match because he is the heir to Mansfield Park, but when she learns about the character of the two brothers, she thinks Edmund would be best. Unfortunately, Edmund has chosen a profession that she disapproves of, and this causes conflict in their relationship.