It is revealed that Cloud was not accepted into SOLDIER, and that the dark-haired SOLDIER in Sephiroth's memory pictures was Aerith's first love and Cloud's best friend, Zack Fair. Cloud had been present during the incident at Nibelheim, but as a lower-level Shinra guard in a unit commanded by Zack and Sephiroth, and kept his identity hidden from Nibelheim's townsfolk, as he was ashamed of failing to join SOLDIER. After Sephiroth's massacre, Zack, Tifa, and Cloud had all confronted him. Tifa and Zack were defeated, but Cloud was able to stab Sephiroth and throw him into the Lifestream flowing below the town's Mako reactor, carrying with him Jenova's head. Rather than dying, however, Sephiroth's mind was crystallized in Mako, where he could influence Jenova "infected" subjects and reconstruct his body using Jenova's cells. Tifa was rescued and taken to Midgar, before Shinra arrived to cover up Sephiroth's massacre. Professor Hojo used Zack, Cloud and Nibelheim's other survivors to create the Sephiroth clones, performing the same enhancements given to SOLDIER members — a procedure which included Mako infusion - and injecting them with Jenova cells. A few weeks prior to the first events of the game, Zack broke free from his confinement, escaping the lab and taking Cloud with him. With Cloud still in a confused semi-conscious state from the experimentation, Zack headed for Midgar, telling Cloud about his entire life in SOLDIER and suggesting they become mercenaries, in attempts to get Cloud to come around. Zack was killed and Cloud was left for dead within sight of the city by Shinra soldiers. Cloud recovered, took Zack's sword and made his way to Midgar's Sector 7 train station, where Tifa found him. Cloud's own aspirations to SOLDIER and Zack's memories and stories combined, with the help of the Jenova treatment, to create a false external persona; a split personality. The voices that Cloud has been hearing through the game to this point is Cloud's actual, original persona, locked away along with his original memories. Shortly after these events, the mission with which the game opens took place.[28] Realizing all of this, Cloud is able to regain his sanity.