On Finnea Prime, she was a net-girl, using the dataport installed on her neck. Through this, she met Draim, who specialized in blackmail and extortion. She worked with him, tapping into computers to get information about people. At first, she separated herself from the actions Draim took on the information she provided, often a mysterious disappearance. Over time, however, the consequences troubled her.
In 2373 she tried to leave the Syndicate. She came into contact with Tauvid Rem, who claimed to have a method to leave. They agreed to meet on Deep Space 9, and so Arissa went to Quark's. There, she met and impressed Chief of Security Odo with her keen observation of Dabo table manipulation via a graviton emitter. Meanwhile, however, Rem was killed by men loyal to Draim, Traidy and Sorm. Because she could not locate Rem, she tried to break into the station's computer, during which she was apprehended by security personnel and brought to Odo for interrogation.
Arissa, avoiding suspicion, claimed Rem had information on her long-lost daughter. When Odo checked her story, they found that Rem was dead, but otherwise believable. Later on, Odo, on a hunch, caught her on the Promenade when she broke into the assay office. When asked if she found anything in Rem's locker, she showed him a data crystal. In order to protect her, Odo had her stay in his quarters. Since first meeting, both had a mutual attraction for each other, and they spent a passionate night together. In the meantime, Starfleet crew studied the crystal to find out what the information was.
Having possession of the data crystal would allow her to contact Draim and offer it in exchange for her life and an exit from the Syndicate. She then stole it from the science lab and contacted Draim. He agreed to the deal, but wanted her dead anyway. He instructed his hit men, to kill her after the crystal was retrieved. They arranged a meeting in a cargo bay. Fortunately for her, another Idanian operative had arrived and helped Odo locate and rescue her from the assassins. The officer would reveal to Odo her real identity.
With the help of Doctor Julian Bashir, both the agent's real memory and Idanian appearance were restored. She said goodbye to Odo, and confided that, even though she was married, the relationship between him and Arissa was real and she would never forget him. (DS9: "A Simple Investigation")
Arissa was played by Dey Young.
Young commented: "I love that role. I enjoyed playing Hannah Bates in The Next Generation very much but I really love Arissa. It was neat to have Odo fall in love with her and he truly meets his match as far as Arissa’s expertise as a spy is concerned. Even though he eventually catches her she’s still able to pull a few fast ones on him. They truly admire each other’s abilities and I believe that same admiration and respect carries into their personal relationship. It was all so much fun. I hope they do decide to bring the character back as I’d love to work on the show again." She added: " You know, I think back on that experience, and playing that role, it is one of my favorite in all my career. Just everything gelled. It was, first of all, working with Rene and the director, John Kretchmer was amazing. He was a wonderful director. And he encouraged the chemistry that Odo and Arissa had, and I think that’s what really gelled in this". "It was a love story. And I literally fell in love with Odo during this time. And, you know, yes, I was supposed to be mysterious, and all of that. But the bottom line of this whole episode is the love that they have for each other, that connection, and then finding out at the end, that she’s someone else that she didn’t even know about, and that she has to go back to her husband when she loves this Odo, you know when she’s fallen in love.” , 
Young didn't mind the Idanian makeup or kissing Rene Auberjonois through his: "They were wonderful lips, let me tell you. I think the beauty of it all was, well, I didn’t have any as you know – Arissa – until the very end, doesn’t have any kind of prosthetics. I had nothing. I had myself. And that was Arissa.” But you know, it’s all in the eyes. Rene’s eyes really came through his prosthetics. And so, it just all was so natural. It was seamless. It just was such a natural thing. It was a beautiful love story. I felt more beautiful as that alien than as Arissa . The wardrobe was beautiful. That is one of my favorite scenes and saying goodbye to him at the very end. I mean it was, it makes me cry even today. It was such a heartfelt goodbye".  According to the script, this name was pronounced as "uh-RISS-uh".