Homeostasis

Homeostasis is opposed to King Drasil and aims to keep Meicoomon's powers from disrupting the balance between the Real and Digital Worlds. It is assisted by Hackmon, who acts as its messenger in the place of Gennai, who is missing.

She is voiced by Lara Jill Miller in Digimon Adventure, while in Digimon Adventure tri., she is voiced by Tara Sands in the English Version.

Appearance
It has no body, it has to possess other people's bodies to communicate.

Digimon Adventure
Homeostasis is the entity that chose the DigiDestined and created their Digimon Partners, Digivices, and Crests. It is assisted by Gennai and other beings like him.

Homeostasis chooses Kari Kamiya as its host, because she is the only one of the DigiDestined who could hear it, and speaks through her to reveal to the DigiDestined why they were chosen.

Homeostasis shows them a holographic recording of the past, when Gennai and his associates were preparing for "the moment when the world would be overrun by darkness" in the basement of what the DigiDestined know as Myotismon's castle, and reveals to them that it chose them back in 1995 when they witnessed Greymon and Parrotmon's fight, then created the Crests and Digivices based on data it scanned from the children at that moment. It also shows them the day the Dark Masters attacked and stole the Crests, how Gennai escaped with the Digivices and Digieggs (also showing the loss of Gatomon's Digieggs), the hatching of the Digimon Partner from those Digieggs, and how they waited for the children to arrive.

Confession
Homeostasis possesses Kari again while she is at school and, in her body, leaves to find the eight Digimon Partners. It warns them of the existential threat that Infected Digimon pose to the balance between the worlds and says that the only way to prevent the total destruction of the Digital World is "a great sacrifice", but it loses its control of Kari before it can say anything else. Maki, who had eavesdropped on the meeting, explains to the Digimon that it was talking about the Reboot.

Loss
Homeostasis possessing Maki Himekawa during the battle between her group of original Chosen Children and the Dark Masters. Homeostasis appears to be the one to give the other Digimon Partners the power to digivolve into the Four Harmonious Ones (Azulongmon, Baihumon, Ebonwumon and Zhuqiaomon).

Coexistence
Homeostasis has decided that Meicoomon has become too powerful and must be destroyed, and tasks Hackmon with killing it. It also believes that DigiDestined have failed to do anything to stop Meicoomon, are no longer of any use to it and must no longer interfere with its will, so the Digital World starts to reject them by randomly changing its terrain and subjecting them to angry Digimon attacks. When DigiDestineds confront Meicoomon in the real world and Jesmon joins the battle, Homeostasis possesses Kari again to try and convince the DigiDestineds not to interfere, but they reject its insistence that the should forget about their friendship with Meicoomon, and Kari forces Homeostasis out of her.

Trivia

 * Homeostasis is left unnamed, and denies that it is the God of the Digital World.
 * It is never referred to by name in the anime, but was given the name "Homeostasis" in the novelization of the series.
 * It is a digital lifeform, and one of the host computers who rules over the Digital World on a Server of the Network.
 * It possesses Kari Kamiya's body three times.