Soran lost his entire family during assimilation of their homeworld by the Borg. Soran himself fled with numerous other El-Aurian refugees. In 2293, his refugee ship, the SS Lakul, was caught in the Nexus energy ribbon near the Sol system. Soran briefly entered the Nexus, but was pulled out again by the Federation starship USS Enterprise-B as he was beamed aboard with the passengers before the Lakul was ripped apart.
Soran subsequently became obsessed with returning to the eternal Nexus, coming to believe that he was being stalked by time. He searched for a means to safely enter the energy ribbon, realizing that approaching it with a ship was impossible and that he had to bring the Nexus to him. However, the only way to alter the ribbon's path – in order to direct it to an M-class planet – was to change the gravitational conditions in the ribbon's vicinity.
For this purpose, Soran allied himself with the Duras sisters, who stole for him trilithium from the Romulans. In 2371, aboard the Amargosa Observatory, he successfully developed a trilithium weapon, capable of collapsing a star by halting its internal nuclear reactions. However, the Romulans attacked the observatory to retrieve their trilithium, and Soran was nearly killed.
Soran survived thanks to the timely arrival of the USS Enterprise-D, and was able to launch his weapon into the Amargosa star. The Duras sisters then transported Soran to the Veridian system, where he had hidden a second weapon on the third planet. The destruction of the Veridian star would cause the ribbon to intersect Veridian III, though at the cost of the millions of lives in the system.
Pursuing Soran, the Enterprise-D arrived at Veridian III but could not locate his weapon on the surface. The Duras sisters allowed Captain Jean-Luc Picard to exchange himself for their prisoner, Geordi La Forge, on the condition that he be allowed to speak with Soran first. Picard was able to stop Soran with the assistance of James T. Kirk, whom he encountered inside the Nexus. Soran died when his weapon exploded on the launch pad, due to Picard's sabotage.
Picard's first attempt to stop Soran failed, and both he and Soran entered the Nexus moments before the Veridian system was annihilated. The Nexus was where Picard encountered Kirk, who had been swept into the Nexus in 2293 from the Enterprise-B. Kirk left the Nexus with Picard to avert Soran's plan, thus consigning Picard's first attempt and the destruction of Veridian into an alternate timeline. It is possible that Soran remains in the Nexus, since he reached it once and time is meaningless there. (Star Trek Generations)