Jenova

'''This is not FF7 canon. Well, some of it is. Most of it is not. This is mostly me trying to keep my notes straight. Spoilers abound.'''

History
Thousands of years ago, Jenova fell to earth. The guardian spirits of Gaia (Summons) at first assumed she was one of them. The ancient humans (Cetra) added her to the pantheon and worshiped her as well. Chaos in particular took a shine to her, since there weren't many other guardians who also specialized in death and entropy. However, the Cetra began to sicken and die and an alarming rate. The other guardians suspected Jenova, but Chaos stood up for her. This is perhaps why so little information or archaeological evidence of his sacred sites remain. By the time everyone realized that yes, it really was Jenova's fault, it was too late to expel her from the Planet. All the guardians could do was seal her away until the Planet recovered enough and they all had the strength necessary to get rid of her.

Mechanics
Jenova is a Hive Queen that feeds on planet energy (aka: Lifestream). Rather than hundreds of worker females, she dominates the wills of males. She does not appreciate other breeding females. The idea is not for more workers, but for mass casualties. Men are easier to boss around and trigger into slaughtering each other. Women are only useful as instigators for further conflict, or possibly more direct killing. For this reason, most women exposed to Jenova develop Geostigma and die immediately. The only exceptions to the rule are sterile females (ie: Rosso), females who have not yet hit puberty (ie: Shelke), and possibly women who are homosexual (this has yet to be proven one way or the other). As far as Gillian, Lucrecia, and the surrogate mothers of the Tsviets are concerned, Jenova was “tricked” by genetic tinkering. Also, the mothers themselves were not directly exposed to Jenova. Most mothers who bear children carrying Jenova’s cells do not survive the birth. Lucrecia died of complications, as did the Tsviet surrogate mothers. Angeal and Genesis’ mothers survived, but were unable to produce further children.

In Men
Jenova is a Hive Queen. She is able to influence men easily, but has a more difficult time with women whom she sees as competition. Rather than hundreds of female workers, Jenova's legion of workers is almost exclusively male.

In Women
Females can be manipulated, but they must be introduced to Jenova's DNA prior to puberty. Although they will develop secondary sexual characteristics, they never menstruate and are completely sterile. Examples include Rosso the Crimson and Shelke the Transparent.

Adult females don't do well on Jenova. Because Jenova sees them as a threat, adult women who are introduced to her cells die of an illness known as Geostigma. It is possible for a mother to successfully carry a child who has Jenova's cells to term. However, complications develop which either result in the mother's death, or render her unable to conceive again. Examples include Lucrecia Crescent (deceased) and Gillian Hewley (only had one child).

Reproduction
The best method of creating children with Jenova's cells is via the father's DNA. The Jenova Project's most successful live birth was Sephiroth, probably because Hojo was using without Professor Gast's knowledge or permission. He did not develop the same symptoms that Angeal and Genesis did. Because their Jenova came from their mothers, the DNA graft was imperfect resulting in several unusual side-effects. Both were able to "copy" their DNA onto others- both human and animal- and bend them to their will. This also endowed the victim with a superficial resemblance to the person controlling them. Second, when injured both Angeal and Genesis developed an auto-immune disorder similar to Lupus that caused their bodies to attack their own tissue. At present there is no treatment or cure.

Adverse Reactions
Some people cannot tolerate Jenova's cells at all. Aside from adult women, adults carrying a summon materia in their bodies will not be able to accept Jenova. They experience a violent reaction that includes nausea, vomiting, a high fever, eventually resulting in Geostigma. Examples include Vincent Valentine and Felicia "Elfe" Verdot.