Companion

Noncorporeal, cloudlike entity of a feminine nature who kept famed scientist Zefram Cochrane alive for 150 years past his normal lifespan. In 2117, the Companion discovered Cochrane drifting in space near death, and brought him to her planetoid in the Gamma Canaris region. She rejuvenated him and cared for him, effectively making him immortal, but doing so subjected him to extreme isolation. Over time the Companion grew to love Cochrane, and so to help alleviate his loneliness, she abducted the crew aboard the Enterprise shuttlecraft Galileo in 2267. One of those crewmen, Nancy Hedford, was terminally ill with Sakuro's disease, and she agreed to merge with Companion to save her life. The resulting individual was still in love with Cochrane, and now that he could return the feelings, they remained together on the planetoid for the rest of a normal human lifetime. (The existence of the Companion and the fate of Cochrane were kept secret from the Federation by Captain Kirk.)