When Sawyer woke up in his cage, Karl did not respond to his questions about where they are and who he is. When Sawyer decided to investigate the cage and its buttons, Karl tried to warn him about the shocking device in the cage's food delivery system. Right before picking the lock on his cage, Karl asked Sawyer about the other survivors from the Oceanic Flight 815 (thus, Karl knew of the crash). (It should be noted that he asked Sawyer the walking distance to where he came from, making it sound as though there was no second island.) He broke out of his holding cell and freed Sawyer as well, apparently to serve as a distraction while he escaped.
Karl was captured by Tom and Juliet, who also captured Sawyer. He was forced by Tom to apologize to Sawyer for using him in his breakout attempt. Then he was taken away, presumably for punishment. ("A Tale of Two Cities")
After Karl was taken, Kate was put in his cell. While Kate and Sawyer were digging up and moving rocks, Alex, who was trying to remain hidden from the rest of the Others, asked Kate about Karl's whereabouts and whether she had seen him specifically in that cage. ("The Glass Ballerina")
Two days later, Alex told Kate that they would kill her "boyfriend" (Sawyer), "just like they killed mine." ("I Do")
During Kate and Sawyer's escape from The Others, Alex met up with them asking them to help her find Karl, who she says is her boyfriend, and at this point Sawyer realized that Karl was the person originally in the cell next to his. If they agree to help her, she promised, she
The three arrived at the Hydra facility bearing the Hydra logo on the main doors. Inside, Karl was found in Room 23, restrained to a chair and wearing LED glasses being forced to watch a bizarre video with flashing images and words, as well as a loud industrial-sounding soundtrack that seemed to be a form of brainwashing. When Kate and Alex freed him from the chair, Karl was not fully concious and had to be carried out by Sawyer.
Just before escaping, Juliet stopped them, forcing Alex to stay on the island by saying that her father would need to see her when he came out of surgery and would never allow Karl to live if Alex left. Juliet allowed the half-conscious Karl to leave in the boat with Kate and Sawyer. ("Not in Portland")
Disclaimer: Karl is a fictional character on the ABC television series LOST. He is played by Blake Bashoff.
LOST was created by J. J. Abrams and is a sole property of ABC.
Karl appears here solely for the purpose of role playing and having fun. No profit is made off of his name, except for extending the enjoyment I feel for this great show.