Jarr was a Zyglak mercenary who commanded a small troop of four other colleagues. Despite the small size of his forces, he was considered a formidable opponent for his strategic thinking, a rare trait among his usually savage species. He was also not intimidated by anybody, not even flinching when he met with Blackout and Malygos. He wore a black top hat and a long black cloak. He also carried various guns and weapons, and was an expert at all forms of combat.
When Blackout and Malygos took the Matoran Universe by storm, Jarr approached them, and demanded that they provide him with protosteel. If they didn't, he said, he would destroy Xia, a vital weapons supplier for the villains. Malygos refused and sent Vahki to kill him, but the terrorist easily defeated them and escaped. He met with his posse; Luux, Marlon, Kinex, and Telino, then he quickly ordered one of his colleagues to detonate the explosives he'd planted around Xia, destroying the island.
The group was attacked by an entire legion of Blackout's horde soon after, but the group trapped them in a canyon and blew it up, killing most of them. Cruelly trapping the live ones on the island, Jarr and his colleagues sped away in their speeder, putting a laser system out: if anybody touched it, some unknown location would explode.
After this, Jarr made an alliance with the Nynrah Ghosts. However, as he was going away, his speeder was destroyed with a hadrium bomb planted by one of Blackout's Rahkshi, and the Nynrah island was nuked by Blackout. Jarr and his colleagues swam to a secret underwater hideout, planning their final attack.
When the Battle of Destral began, Jarr and company appeared and held Blackout at gunpoint, but the Makuta easily disarmed them. Xintrix and Grahmah then joined the battle, and the latter blasted them out of the building and into the sea. Jarr's fate afterwards is unknown, though it was implied that he is now living on the Red Star.