Perrin was a female Human in the 24th century and last wife of Ambassador Sarek. Perrin had a great admiration for Sarek and was extremely loyal. She knew Sarek loved her, even though he could not express it, being a Vulcan.
In the 2360s, she, along with others, noticed that Sarek was beginning to lose his Vulcan control over his emotions, for example, not being able to meditate. She later learned it was Bendii Syndrome, but it was so gradual that she did not really think anything was wrong. She knew that his personal assistant Sakkath was discretely helping him maintain discipline. However, knowing how important the Legaran Conference was to him and his career, she agreed to maintain the secrecy. She believed Sarek could complete this last mission to end his career with dignity.
In 2366, she went with Sarek on board the USS Enterprise-D. She was happy to meet Captain Jean-Luc Picard, as Sarek took some interest in his career. Even though she helped to isolate Sarek, she agreed to ask him to come to a concert held in his honor. However, she noticed Sarek was crying during the performance, and left with him immediately. Later, when Picard confronted her with his suspicions of the disease, she denied it, but was forced to tell Sarek the truth when he overheard them. Afterwards, she suggested to Picard that he take part in a Vulcan mind meld with Sarek to help him complete the mission. Fortunately, it was successful, and she left with Sarek back to Vulcan on the USS Merrimack. She expected to need to take care of Sarek more and more as time went on. (TNG: "Sarek")
Before Sarek's death, Captain Jean-Luc Picard visited Vulcan to talk with him about his son Spock's apparent defection or abduction to Romulus. Perrin came aboard the Enterprise-D and met with Picard, who had once taken part in a mind meld with Sarek. Perrin did not get along with Spock. She was upset with him because he didn't bother to say goodbye to his father. She was further upset because Spock had publicly challenged Sarek's arguments during the debate over the Federation-Cardassian War.
She was able to inform Picard that Spock was definitely not abducted, that he put his affairs in order before leaving Vulcan. At first she did not want to allow Picard to see Sarek because he was so ill, and she doubted Sarek knew why Spock left. She finally consented to let Picard see him because of the mind meld they had shared.