What is the complication and thesis of the last leaf by o Henry?

The complication in "The Last Leaf" by O. Henry arises when Johnsy loses hope after catching pneumonia. She becomes fixated on the idea that when the last leaf falls from a vine outside her window, she will also die. The thesis of the story explores themes of sacrifice, friendship, and the power of hope in overcoming adversity. Old Behrman's selfless act of painting a leaf on the vine during a storm symbolizes the resilience of the human spirit and the enduring impact of small acts of kindness.