Charlotte is someone who Stephen met sitting next to each other on a flight from Charlotte to Detroit. She seems to be around 77 to 78 year old woman (as of Janurary 2018) who lives in New Jersey. She has children but seems to not have a husband.
In June of 2008, Stephen happened to sit next to Charlotte while on his way to Wisconsin to see Mallory for the first time on a flight from Charlotte to Detroit. Stephen started to talk to Charlotte about Mallory and his feelings for her. At the end of the flight, Charlotte wanted to know what would be the outcome of what he told, so she gave him her address and they split ways. A week later after seeing Mallory, he sent her a handwritten letter, and sent a picture of them together.
3 years later on Day 573, Stephen recieved a letter from Charlotte. In the letter she says that her husband had died, her children refuse to talk to her and her brother's grandchildren are taking her to court. However, she said that she feels that Stephen and Mallory make a great couple. She predicted Stephen and Mallory's marriage. At the time they were less than two months away from their wedding. He responded to her after the wedding was over.
Half a year later on Day 765, Charlotte just so happened to be stopping by Myrtle Beach so they decided over the phone to have lunch together. According to Stephen, she was doing fairly good.
A year later, Stephen sent another letter to Charlotte during Christmas 2012, but never heard back.
3 years later on Day 2249, Charlotte called Steve Georg's phone, Stephen's Dad, and left a voicemail and said her phone number in it. Steve then called Stephen, saying that he thought it was the same Charlotte Stephen talked to while on the flight to Detroit. Once Stephen called, sure enough it was the same Charlotte. They had a two hour conversation. She talked to both Stephen and Mallory.
They have not talked to each other since then but the last time Charlotte talked to Stephen she mentioned, "I'll call you when you least expect it."