Kurros was the spokesperson of the "Think Tank", a diverse group of alien scholars who traveled about the galaxy, offering to solve people's problems for a price. The "Think Tank"'s primary intermediary to their clients, he was a brilliant tactician who delighted in solving problems and being challenged.
Kurros joined the "Think Tank" at a very young age. It saved his planet from a cataclysmic problem, and Kurros was traded as payment. His fellow companions were a jelly fish-like lifeform, suspended in fluid, the humanoid Fennim, a bioplasmic lifeform which was thousands of years old, and an artificial intelligence. They lived on a vessel made of a neutronium alloy residing in subspace.
Kurros and his group had learned about the USS Voyager and, in particular, Seven of Nine, in 2375. As a former Borg drone, she was a very intelligent and unique person, making her desired as another colleague in the group. They arranged a plan to force her to join the group by hiring the Hazari as bounty hunters to capture Voyager, while at the same time making a deal with Captain Kathryn Janeway to give them a way out of their predicament, with Seven as part of the payment.
Kurros hired the Hazari as a Malon through an isomorphic projection. After the Hazari attacked and Voyager realized it was cornered, Kurros then appeared as himself to Janeway on her ship for introductions, and told her that they could solve her Hazari problem. He told her that his group of problem-solvers had cured, for example, the Phage which had been afflicting the Vidiians. He gave her a bit of information on the Hazari locations, just enough so she would take him seriously and board his ship. He impressed Janeway, and received data from her on what they could provide as payment. Later, he gave her his response: the quantum slipstream drive, Neelix's recipe of chadre'kab, Chakotay's Olmec figurine, and Seven of Nine. Janeway refused, but Kurros encouraged her to ask Seven and returned to his ship.
Unbeknownst to Kurros, Voyager was able to capture a Hazari shuttle and its crew. From its computer, the crew determined Kurros' plan. Furthermore, he was not aware that Janeway enlisted the Hazari by exposing the trick and made a deal with them: they would stop their attacks and she would deliver the "Think Tank"'s ship to them. Kurros appeared to Voyager again to "witness" that Seven had left the ship without authorization to settle the deal. On Kurros' ship, he was delighted to see Seven and tried to convince her that her choice would be beneficial, however, he sensed deception once she interfaced with the ship's communication system. At the same time, Seven disabled Kurros' ability to communicate with the other beings in the "Think Tank", compromising its defenses, and the Hazari fired spatial charges which pulled Kurros' ship out of subspace and commenced their attack. He furiously tried to repair the ship as Seven was transported away back to Voyager and Janeway left, notifying Kurros that she hoped he could solve his own Hazari problem. (VOY: "Think Tank")