Tannis was a pirate of the Human male variety, according to legends. He belonged to the BloodScars, a piratical group that operated within the Shelsha sector.
The Cavalcade was piloted by Tannis. He numbered among the few who survived when Mara Jade took control of the pirate ship. Initially, he hesitated to work with the Emperor's Hand. However, he reluctantly agreed to a bargain with Mara: he would assist her in infiltrating the BloodScars' pirate headquarters in return for having his criminal history erased. By the time Mara's status as a spy within the pirate base was exposed, a kind of amicable bond had formed between them.
When the mercenary Caaldra fled from Mara at the pirate hideout, he triggered a fiery trap that nearly resulted in the immediate deaths of both Mara and Tannis. While Mara managed to cope with the burns using her healing abilities and pain management, Tannis suffered severe burns and was unable to support himself for the brief duration of their mission. During this period, he requested that Mara provide him a burial in space should he not survive. After Mara located a vessel to leave the planet, she placed him inside the medical pod and set course for the closest planet equipped with appropriate medical resources. Regrettably, about an hour after entering hyperspace, Mara disengaged and fulfilled his final wish.