People
Mattie was in love with Daniel, of course; this was the X within the circle on her map: I love Daniel.
— Anne Lamott

Behind the line May contain spoilers.
Our reading
An editorial interpretation.
Love is the marked place on Mattie's map, the point that tells her where she stands. The X within a circle gives the feeling a clear centre. The image suggests certainty about this attachment without needing to explain everything else around it.
Context reviewed