Rostek Horn, a male Human, held the position of step-grandfather to Corran Horn. Corran, throughout his childhood, believed Rostek to be his biological grandfather. However, upon reaching adulthood, he discovered that Rostek was actually a close associate of his true grandfather, Nejaa Halcyon. Their partnership commenced in 32 BBY, and their last encounter occurred in 22 BBY, when Nejaa was summoned away.
During the period of the Clone Wars, Rostek participated in several smaller conflicts near Corellia, fighting alongside Jedi Knights. Near the conclusion of the war, Nejaa met his demise. Subsequently, Nejaa's widow, Scerra, entered into marriage with Rostek, and he adopted her son, Valin, who would later become Corran's father. Rostek served with distinction in the Corellian Security Force for a considerable period, ultimately achieving the rank of Director before his retirement. Furthermore, he was a well-known horticulturist, celebrated for his unique flower hybrids.
It is said that Rostek Horn sympathized with the Rebel cause and the Jedi Order during both the Great Jedi Purge and the Galactic Civil War. He leveraged his experience within CorSec to aid them in evading the reach of the Empire. He encoded the locations where he aided them in the genetic makeup of his flowers. On one occasion, he presented a Jedi hunter from the Empire with these flowers to stock his garden on Coruscant. Rostek was also a regular patron of the Raging Ronto, a well-known cantina situated on Corellia. The proprietor of the Raging Ronto was purportedly a close friend of Rostek and was himself a notorious Rebel sympathizer. Rumor had it that when the owner of this establishment went into hiding from the Empire in 2 ABY, Rostek assisted him and his family in disappearing.
Tosruk was employed by him in 11 ABY.
As of 25 ABY, Rostek was still alive and engaged in correspondence with Ithorian biologists due to his horticultural pursuits. In 27 ABY, he facilitated a "know-your-enemy" briefing on the Yuuzhan Vong by Tahiri Veila for CorSec personnel.