Arissa.
Arissa's true appearance.
Arissa (played by Dey Young) was born on Idania and is married.
In 2371 'Arissa' joined the Idanian Intelligence Agency and volunteered to infiltrate the Orion Syndicate. Because of the nature of this mission she had to undergo reconstructive surgery and her memories would be replaced, temporary stored in a data crystal. After this identity change she would be known as Arissa and was left on Finnea Prime without any knowledge of her former life.
During her time there she ended up with a dataport when she became a net-girl. Here she met Draim a member of the Orion Syndicate specialized in blackmail and extortion and got involved with him, doing things like taping into computers to get information about people.
In 2373 she tried to leave the Orion Syndicate which brought her to Deep Space Nine. Here she was noticed by Chief of Security Constable Odo while being in Quark's Bar due to her keen observation when she noticed someone who manipulated the Dabo table for his friend via a graviton emitter.
While being on Deep Space Nine she tried to contact Tauvid Rem who had a data crystal for her with information by which she could break free of the Orion Syndicate. Because she could not locate Tauvid Rem she tried to break into the stations computer where she was apprehended by security personnel and brought to Odo for interrogation.
When Odo checked her story they found that Tauvid Rem was killed. Later on Odo caught her on the promenade when she broke into the assay office. When asked if she found anything in Tauvid Rems locker she showed him a data crystal. During the rest of the investigation Odo got romantically involved with Arissa.
At a certain point she contacted Draim to make a deal with him, her leaving the Orion syndicate while Draim got the crystal. When she contacted Draim's people to finalize the deal she found out that Draim wanted her dead anyway. Fortunately Odo and a Idanian Intelligence Officer rescued her from Syndicate assassins.
With the help of Doctor Julian Bashir her memories from the data crystal where restored and he also restored her original Idania appearance.
When she said goodbye to Odo she told him that she was married and that the relationship between him and Arissa was real and she would never forget him. (DS9:"A Simple Investigation")