Sephiroth Clone

The Sephiroth Clones are a group of test subjects used in the Project S portion of the Jenova Project in Final Fantasy VII. They were injected with Jenova Cells by Professor Hojo to test Jenova's ability to recall her scattered cells into a "Reunion", in what he called the "Jenova Reunion Theory". There are at least fourteen known test subjects, but Hojo rejected many as "failures", leading the exact number of unfortunate people who were mutilated by this subject to be unknown.

"Clone" is in fact a misnomer. Sephiroth Clones are not genetic copies of Sephiroth, but rather those who carry the cells of Jenova, which Sephiroth exerts his will through to use the 'clones' as his puppets.

In the original Japanese script, they were not referred to as clones at all, but as Sephiroth Copies.

Story
After the events of the Nibelheim Incident, Professor Hojo rounded up the survivors of Sephiroth's rampage. He injected them with Jenova Cells and exposed them to Mako Energy, similar, if not identical, to the creation of a SOLDIER. However, these people were not the finest in physical and mental fitness, thus they could not keep their own egos. They became just shades of Jenova. Since Jenova was a puppet of Sephiroth, the Clones too became fanatics who would do anything for their master Sephiroth. Those that were proper slaves were engraved with a number someplace on their bodies, those that failed and kept some shred of their egos were left to die. Cloud Strife would have been a success as well had not Zack intervened and rescued him from the Shinra Mansion. Zack, also a Sephiroth Clone, was a total failure. He seems to not have been mentally affected by the experiment at all due to previously being unaffected by the identical SOLDIER procedure.

The 12 Sephiroth Clones that suceeded become the group of fanatics that follow Sephiroth around in Final Fantasy VII. Strangely, the Sephiroth Clones did not migrate to Jenova as Hojo predicted. Rather, the twelve began to head to the Northern Crater and hunt for the Black Materia for Sephiroth. Jenova herself broke out of Shinra Headquarters and moved towards Sephiroth in his form and under his complete control. Cloud was influenced by both the unconscious need for Reunion and his drive to avenge Nibelheim.

In the end, only Cloud survived the journey to the Northern Crater. All the others died on the way. Because Cloud was simply a semi-failure, he had his own mind and ego, but Sephiroth could take complete control of him at will. However, this power seems to be somewhat limited, as Cloud refused Sephiroth's command to kill Aerith Gainsborough. When Sephiroth reveals that Cloud is a slave and his past an illusion, Cloud breaks down and accepts his fate as a Sephiroth Clone. He hands Sephiroth the Black Materia and is flushed into the Lifestream.

Later, with the help of Tifa Lockhart inside his subconscious, Cloud rebuilds his psyche and is restored to normal humanity. With that, the Sephiroth Clones are finished.

However, in the film Final Fantasy VII: Advent Children, the children infected with Geostigma each carry a small portion of Jenova's cells. Kadaj tells Rufus Shinra that "[his] brothers and sisters who share Mother's cells will all assemble" as part of the Reunion he and the other Remnants of Sephiroth are planning. Thus, while those infected with Geostigma are different from and are never refered to as Sephiroth Clones, their role in the film is roughly the same.

List of Known Sephiroth Clones
Below is a list of every Sephiroth Clone that has been revealed. This list is certainly missing several Clones, for many numbers are missing.

*II: The man suffering from Mako poisoning in Sector 5. Upon returning to Sector Five after receiving the Sector Five Key from Bone Village, residents report seeing him leave "mumbling something about a "reunion". *IV: One of the half-dead people found in Nibelheim. Gives an item to party like all the Clones in Nibelheim. *V: One of the half-dead people found in Nibelheim. *IX: Exited from the Temple of the Ancients before dying. Had a tattoo on the back of his neck. *XI: One of the half-dead people found in Nibelheim. *XII: One of the half-dead people found in Nibelheim. *Cloud Strife: The main character of Final Fantasy VII. Went into a vegetative state after being injected with Jenova cells and exposed to Mako, and was labeled a failure. This assumption proved to be false, as he was eventually able to regain consciousness and was able to be controlled by Sephiroth to an extent. One of the only Clones to make it to the Northern Crater, but later threw off the control of Sephiroth. Does not have a number. *Zack Fair: The main character of Crisis Core -Final Fantasy VII-. Was able to resist the effects of the Jenova cells with his strong will, and was therefore labeled a failure. Died fighting the Shinra Peacekeeping Troops outside of Midgar. Does not have a number.
 * I: A young man around Cloud's age. Went from North Corel to Gold Saucer. Had a tattoo on the palm of his hand. Asked Dio if he had a Black Materia, as Dio later tells Cloud in the Speed Square.
 * VI: One of the half-dead people found in Nibelheim's Inn.
 * Mini-Clone (1): A half-dead person, (possibly a child) found in an attic in Nibelheim along with another mini-clone, no number is given. Most likely number VII or
 * Mini-Clone (2): A half-dead person, (possibly a child) found in an attic in Nibelheim along with another mini-clone, no number is given. Most likely number VIII or
 * Unknown-Clone (1): A Half-Dead Person found outside Nibelheim's Mansion, Possibly Number X or
 * A Half-Dead Person found outside Nibelheim's Mansion, Possibly Number or X.
 * Red XIII: at one point fears he might be a Jenova Clone due to being given a number by Professor Hojo, but this was involving an unrelated experiment.

Development
In an early version of the game script, the Sephiroth Clones were not people, but rather parts of Jenova floating in the air covered by their cloaks. During important plot points, they would reveal themselves to be pieces of Jenova's body: her right arm, heart, etc. They also replaced Sephiroth in several scenes, such as the pivotal one in the Forgotten Capital.