Arne Darvin was a Klingon, surgically altered to appear Human, who served as an operative for Klingon Intelligence, infiltrating the Federation's authorities on agriculture during the 2260s.

In 2268, on Deep Space Station K-7 while posing as an assistant to Nilz Baris, the Federation Undersecretary for Agriculture, Darvin poisoned a shipment of quadrotriticale grain, which was destined for Sherman's Planet. Shortly after, Darvin's true identity as a Klingon was exposed by Captain James T. Kirk, using a tribble.

After being disgraced, Darvin was abandoned by the Klingon Empire and wandered from place to place posing as a merchant named Barry Waddle, eventually becoming trapped on Cardassia Prime during the Klingon-Cardassian War. While on Cardassia, Darvin learned of the Orb of Time and plotted to use it to change his past and gain revenge on Kirk. His opportunity came when the USS Defiant was assigned to transport the Orb back to Bajor in 2373.

As Waddle, Darvin gained passage aboard the Defiant and used the Orb of Time to transport the entire ship back to 2268, where he planted a tricobalt bomb inside a tribble in the storage compartments aboard K-7. The crew of the Defiant successfully prevented the bomb from killing Kirk, minimizing the changes in the timeline. Darvin was captured and returned to Federation custody as well as his past self getting caught again.