Ingrid Connelly was a selkie. She was stuck in her human form some time in the late 1600s, when she met and married Tidh Connelly. When her pelt was found by Lambert, he used it to control her to help his piracy. She was finally freed in 2006, when Tidh returned her pelt to her.
Ingrid first appears as a woman separated from her pelt and, by extension, the sea in Kirkwall in 1683. Nothing is known of her age or youth.
She met Tidh while he was on shore leave, and they had a fast romance. When a storm threatened his ship two days later, she used her powers over the sea to calm the storm and save Tidh and the rest of the crew; impressed with her ability, the captain of the ship welcomed her aboard with the task of easing their travels. She was highly successful at this, to the point that she was credited with the ship's acceptance to privateering and ultimately Tidh's promotion to captain in 1685. At this point, she married Tidh.
When a pirate captain named Lambert found her pelt, he used it to control her and steal her away from Tidh's ship in 1688. Aided by her magic, the Heretic Wind became a fearsome pirate ship with a legend for being impossible to catch. She remained under his control until 1694, when Lambert was killed in a firefight with Tidh and buried with her pelt.
Nothing is known about how she spent the next 300 years, except that she apparently found a way off the island where Lambert was killed. She returned to Tidh when he summoned her with the aid of her pelt, which was then returned to her. Finally free to determine her own destiny, she helped Tidh deliver Benedict and Akshainie to Iravati and accompanied Tidh to seek his freedom from The Deep.