Su-mil, hailing from the planet Kariek, was an Eickarie. Not long before the year 22 ABY, he enlisted in the armed forces of the Empire of the Hand, becoming a stormtrooper within the ranks of the 501st Legion, where he adopted the combat name Grappler.
Initially, Su-mil fought for freedom as part of the resistance movement on his native planet. His initial encounter with the four soldiers of stormtrooper Unit Aurek-Seven occurred during the fight to free Kariek from the control of "the Warlord." Following this battle, Twister, the squad's commanding officer, extended an invitation for him to join the Empire of the Hand's military.
After becoming a stormtrooper, Su-mil took Twister's place in Aurek-Seven following Twister's departure. His rise to the role of squad leader appears to have been swift, and he continued to serve with the squad until at least 22 ABY. In that particular year, Grappler, along with the other three members of his unit, accompanied Chak Fel on a mission to the Redoubt, where they took part in the Battle of the Redoubt.