Seska

Seska was a Cardassian female born on Cardassia sometime in the 2340s.

Life Undercover
In 2361, Seska was made an intelligence operative for the Obsidian Order, and began a ten-year career as an undercover agent. In 2367, Seska underwent surgical operations to transform her into a Bajoran and sent to Bajor to spy on the Bajoran Resistance. Once the Occupation of Bajor ended in 2369, Seska was assigned to spy on any lingering Bajoran freedom fighters, and later the Maquis. She also attended Starfleet Academy. She acted as a informant for Gul Aman Evek, though she was unable to give vital information on Maquis base.

In 2368, Seska was contacted by former Starfleet officer, Chakotay, after he resigned his commission to help fight the Cardassians who had attacked his homeworld, Dorvan V. Seska helps Chakotay in joining the Maquis and she serves under Chakotay on his various commands until 2371. For a brief time, Seska and Chakotay have a relationship. 

True Colors
Following the Val Jean 's journey into the Delta Quadrant in 2371, Seska was forced to join the crew of the USS Voyager and maintain her Bajoran appearance. She disliked having to rely on Starfleet for returning her to the Alpha Quadrant and was deeply angered when Captain Kathryn Janeway destroyed the Caretaker's Array, their only way home, in order to save the Ocampans from the Kazon. She was so angry that she began to show her support for Chakotay stage a mutiny so that the Maquis could take over and get the ship home. 

Her overt anger began to fade away and she settled into her duty assignments in Main Engineering but was still looking for any opportunity for her to return home or make life easier. A few weeks later, Seska was one of several conspirators who attemped to use a Sikarian spatial trajector to hasten their return home, however that attempt failed. 

Seska also managed to establish contact with the Kazon-Nistrim and promised to share with them the secrets of replicator technology in exchange for Voyager 's safe passage. However, when Voyager found a disabled Kazon raider an away team discovered that they had attempted to build their own replicator using provided schematics. When Seska was seriously injured trying to cover her tracks, her true Cardassian heritage was revealed by The Doctor. Before she could be arrested, she had herself beamed to First Maje Jal Culluh's ship, where she became his consort. 

Culluh decided to keep Seska aboard his ship and took her as a consort. In 2372, Seska and Culluh hatched a plan to board Voyager and steal transporter technology and use it as a bargaining chip to bring the other First Majes under his control. While the attempt was successful, the transporter module was destroyed by Commander Chakotay. 

Shortly after this incident Seska became pregnant with Culluh's child, but she claimed it was Chakotay's. A few weeks later, Captain Kathryn Janeway proposed an alliance with the Nistrim, but Culluh refused to be dictated to by a woman and the talks collapsed. Although he agreed to attend a meeting on Sobras with Janeway, the Trabe leaders, and the other First Majes, the meeting was attacked by the Trabe as an attempt to assassinate the Majes, and Culluh barely escaped with his life. 

By the end of 2372, Seska's baby had been born and they set about using him as a pawn to lure Voyager into a trap and seizing control of the ship. The attempt was successful and the crew were abandoned on Hanon IV, with only The Doctor, Lon Suder aboard Voyager and Tom Paris away from the ship. Thankfully, the three managed to sabotage the ship and led a Talaxian fleet against Voyager to free the ship. Unfortunately, Seska was killed in the battle, but Culluh managed to escape with the baby.