Reunion Theory The Reunion Theory is a term in the " Compilation of Final Fantasy VII " . It is a scientific theory proposed by Professor Hojo positing that Jenova cells , once separated , will seek to reunite and return to the main body , influencing the minds of creatures they have been implanted in to do so . Story . " Final Fantasy VII " . Hojo put his Reunion Theory to the test in the aftermath of the Nibelheim Incident . The survivors of Nibelheim , including Cloud Strife and Zack Fair ( and excluding Tifa Lockhart , who had been rescued before Shinra arrived ) , were rounded up and injected with Sephiroth cells , Sephiroth having merged with Jenova cells while still in the womb . The subjects were exposed to Mako in a procedure similar to the augmentation done to SOLDIER members . As the Nibelheim survivors did not have the mental or physical strength to keep their sense of self , they became mindless puppets devoted to Jenova and Sephiroth called Sephiroth Clone s . Zack , being a SOLDIER , resisted the effects , but Cloud succumbed and developed Mako poisoning . Hojo labelled the two as failures and held them in Shinra Manor for years , while the successful Sephiroth Clones were tattooed with numbers to keep track of them . Five years after the destruction of Nibelheim , Sephiroth ' s body at the North Crater sends out a call for the Jenova Reunion . The main body of Jenova kept at Shinra Headquarters awakens , escapes , and takes on Sephiroth ' s form . It attacks President Shinra , and in the chaos Cloud and the members of AVALANCHE imprisoned in the building are freed . Recognizing Sephiroth ' s Masamune near President Shinra ' s body , Cloud and AVALANCHE pursue the shapeshifted Jenova across the Planet to settle Cloud ' s grudge with him . Unbeknown to them , the reason Cloud is driven to chase Sephiroth is due to the call for the Reunion influencing his thoughts . At this time the other Sephiroth Clones begin to move , some seeking the Black Materia Sephiroth needs for his plans . Cloud and the other Sephiroth Clones gather at the Whirlwind Maze , where the party witnesses Jenova in Sephiroth ' s form kill most of the Clones , sending them into the Lifestream , and then transform into Jenova∙DEATH . The party defeats Jenova and reclaims the Black Materia . In an area abundant in crystallized Mako they meet Hojo , Rufus Shinra , and Scarlet . Hojo reveals his Reunion Theory , explaining he expected the Sephiroth Clones to meet at Midgar where Jenova ' s body was being held , but Sephiroth ' s will overrode the Reunion instinct and brought the Clones to where he was instead . Cloud , the last Clone , arrives at Sephiroth ' s body to deliver the Black Materia . The Remnants of Sephiroth seek Jenova ' s remains , recovered and hidden by Shinra Electric Power Company . Kadaj tells Rufus Shinra the plague Geostigma that has infected the Planet is Jenova ' s legacy , and Vincent Valentine later tells Cloud it is caused by Sephiroth ' s cells corrupting the Lifestream and infecting the bodies of those who come into contact with the tainted Lifestream . In a sense , this makes them similar to the Sephiroth Clones . The Remnants ' goal is to find Jenova ' s cells to bring about Sephiroth ' s rebirth . As they are formed from spiritual energy , they are not complete copies of Sephiroth , and having no Jenova cells , he cannot exert control over them directly . The Remnants are guided by their instinct to find Jenova , believing her to be their mother , but without Jenova cells they have no Reunion instinct and cannot sense her . Loz and Yazoo gather children infected with Geostigma from Edge , Denzel among them , and take them to the Forgotten Capital where Kadaj activates the Reunion instinct within them . The children lead the Remnants back to Edge , gathering around the Meteor Monument in the center of town , and the Remnants destroy it with Bahamut SIN , believing Jenova to be held inside the monument . As Cloud and his allies battle Bahamut SIN , Rufus reveals to Kadaj he has been keeping Jenova ' s remains under his cloak , and in the confrontation Kadaj seizes the box and the Remnants escape into the Midgar ruins . As Kadaj battles Cloud , the box containing the cells is sliced open and Kadaj merges with the contents . Sephiroth exerts his power over Jenova ' s cells and shapeshifts Kadaj into a new body for himself , completing the second Reunion . " Dirge of Cerberus - Final Fantasy VII - " . It is revealed that near the end of " Final Fantasy VII " , before AVALANCHE killed Hojo in Midgar , he uploaded a digital copy of his mind into the Worldwide Network . When Meteor almost struck the Planet , the power outage put the network off - line , and Hojo ' s digital copy was fragmented . Three years later , the World Regenesis Organization reactivates the network , allowing Hojo ' s fragments to reform and take control of Weiss the Immaculate while he is engaged in a Synaptic Net Dive . Hojo tells Vincent he considers his digital reformation and control of Weiss a " neo - Reunion " .