Final answer:
Johnsy's command for Sue to open the green shades in literature symbolizes a desire for light or a change, leading to surprise from an unexpected outcome or revelation. This narrative device creates suspense and affects the storyline.
Step-by-step explanation:
Johnsy commands Sue to open the green shades so that she can see the ivy vine she has been watching from her sickbed. Both of them are taken by surprise by the events that follow due to the emotional or plot turn that typically follows such a request in literary narrative, creating suspense or leading to a notable change in the characters’ situation or in their understanding.
The exact reason for their surprise is not included in the provided text references. However, in literature, a command to open the shades often indicates a desire for light, hope, or a change in perspective, and the surprise can be the result of an unexpected outcome or revelation that follows the action of opening the shades, which has the potential to significantly affect the storyline and the characters involved.