Miri

Miri was from an Earth-like planet somewhere in the Milky Way Galaxy. Like all the survivors on her world, Miri was infected with a horrific disease which had resulted from an experiment in life prolongation. This disease had killed all the adults and left behind children that would live to be immensely old. Unfortuneately these children would also contract the disease and die upon entering adolescence which explained why there were no adults. Miri was born some time around the Earth year 1955. So when she met the USS Enterprise landing party in 2266, she was over 300 years old! The landing party found Miri hiding in an abandoned building. At first, she was terrified of them but eventually they won her trust. From her they learned that the "grups" (the sick and dying adults) had become insane, and that the children, or Onlies, had come to fear and hide from them. Soon the landing party contracted the life prolongation disease and therefore could not return to the Enterprise. With Miri's help, they found the building where the scientific research had taken place and Dr. McCoy immediately began working to find a cure. Miri was glad to perform small tasks for them as she had developed a crush on Captain Kirk. Nothing ever came of it though as Kirk had made it a practice not to get romantically involved with older women. Dr. McCoy's research was successful and the horrific disease, which had been created over 300 years ago, was eradicated. Later, when the Enterprise departed from her world, Miri and the other Onlies were left in care of medical specialists from the starship while more adults were on the way to help her planet become a civilized and prosperous world once again.