Tobal Siy served as an Imperial commander and oversaw the Star Destroyer called Thunder. His duties frequently involved pursuing Rebel smugglers operating within his assigned area. This presented a significant obstacle for Siy, given the smugglers' uncanny ability to anticipate his movements. Siy began to believe that a mole had infiltrated the Imperial forces. Unbeknownst to him, his very own protocol droid, N-3PO, was the spy, secretly a Shard in disguise.
Siy experienced considerable annoyance due to his circumstances, which occasionally led to headaches stemming from his inability to capture the elusive Rebel smugglers. He sought relief from these headaches through the consumption of alcoholic beverages and pain medication. He placed a great deal of faith in his protocol droid, and when N-3PO inquired, Siy would share his strategic plans for future operations aimed at apprehending the smugglers.
- " Alien Encounters: The Shard " — Star Wars Adventure Journal 15 (First mentioned)