One night in the woods, Jack Ramsey fell into a hole, and broke his leg. He woke up to find himself tied up in an underground cave, with his leg completely healed. In the cave with him, was a girl. After she untied him, Jack saw...Livvie! However, it wasn't Livvie. The cavegirl was identical to Livvie, but she said her name was Tess. She didn't know where she came from, or anything much about the outside world; all she had was an old doll. Jack taught her things, and slowly began to fall in love with her. Now Jack wanted to take her back to Port Charles.
When Tess wandered to General Hospital, she miraculously brought Kate Reynolds's boyfriend, Brennan, out of a coma. It was then that everyone discovered she had healing powers. When Livvie and Tess finally came face to face, Livvie was horrified, and denied that Tess was in anyway related to her. Livvie wanted Tess out of the way, so she could have Jack back. While arguing with Tess, Livvie scratched Tess's arm and it started bleeding, but Livvie found she also had a cut on her arm in the very same place. Livvie believed Tess was a monster Rafe created to destroy her. After locking Tess in a trunk (nearly killing her), Livvie discovered that whatever happened to Tess, happened to Livvie herself. Livvie and Tess started to form a relationship.
Jack and Ian administered Tess to DNA tests, to determine who she was. Jack was stunned to read the results. According to them, Tess wasn't human. A recently returned Caleb Morley (under the name Stephen Clay) revealed that he created Tess, by pulling the good part of Livvie (which would be Tess) out of her, during the summer of 2001.
On the docks, Livvie confronted Joshua, Caleb's right hand man, when he tried to kill her by throwing her into the water. Tess arrived, and Joshua threw her in with Livvie. To save Livvie from drowning, Tess combined Livvie with herself. Caleb tried to bring back Livvie, but Tess wouldn't let him, trying to protect Livvie from him.
Soon after, Jack and Tess got married, and Jack tried to protect Tess from Caleb. But Tess, much as Livvie had been, was attracted to Caleb and could not stay away from him. She shared with him that she could feel Livvie inside her, struggling to get out, but that she wouldn't because she wanted to protect Livvie from Caleb. Tess also tried telling this to Jack, but he didn't want to believe that evil Livvie had anything to do with the goodhearted Tess. He was eventually forced to face the fact that Tess was telling the truth when yet another DNA test proved that Tess now had DNA, and it was an exact replica of Livvie's.
Meanwhile, Caleb had a music box created for Tess; when opened, it let Livvie out. But Caleb, drawn to Tess just as much as he had been drawn to Livvie, eventually destroyed it and confessed to her one day that he loved her for she was--Tess. Tess, who had been trying to tell Jack for ages that Livvie was a part of her (he was in denial), eventually left Jack to be with Caleb. But Caleb realized that he had to do what was best for his beloved one, and make Tess and Livvie one whole person again. He re-created his and Livvie's wedding night from 2001, and made the two women into one whole one--Olivia.