- You may be looking for Joan's namesake from the original novel.
While at Farringham, John Smith fell in love with her. He showed her a journal in which he had written down his dreams, which were his adventures with Rose and Martha before he was human. After John Smith became the Tenth Doctor again, she asked him if he could change back into John. He said yes, but when she asked if he would he said no. When he asked her to join him as a companion, she dismissed the idea immediately, saying that John Smith was dead and the Doctor just looked like him. She then asked the Doctor, "If you hadn't decided to come here on a whim, would any of these people have died?" He looked at her without answering. She dismissed him and, after he left, broke down, clutching John's journal.
In an alternative future viewed by her and John Smith, she became his wife. They had two children and a number of grandchildren as they lived long, happy lives together. (TV: Human Nature / The Family of Blood)
In the proper timeline, Joan's great-granddaughter Verity Newman published the Journal of Impossible Things as a true story told from Joan's perspective and told Joan's story to people wanting to purchase the book, so Joan would be remembered. She was visited by the Doctor before he regenerated into his eleventh incarnation. She said that, in the end, Joan was happy and asked if he was. The Doctor left without answering. (TV: The End of Time)