Snail's theory

The Shivans

A long while before, the Shivans were the intergalactic masters of subspace. Controlled by a Hivemind and with extremely advanced technology, the Shivans had access to unlimited labor and resources spanning multiple galaxies. The Shivans traveled between galaxies with the use of 'Super Jump Nodes' (or Supernodes) at which point the subspace node was exceptionally large and very powerful.

The Shivans had multiple frontier fleets which ventured to the further reaches of the universe, as well as larger fleets nearer to the center protecting the Hive. Each of these fleets was placed very far away from each other, sometimes with little or no contact with the other fleets or the Hive. In the event that a fleet lose contact with the Hive, the Shivans have special 'Sub-Hives' or 'Backup-Hives' which control the force under its command until it either comes back into contact with the Hive or another larger Shivan fleet.

Cataclysm

After a while (around 200,000 to 10,000 years ago), a huge subspace cataclysm occurred. A sort of space-quake, the cataclysm destabilized hundreds of Subspace Nodes all over the known universe, throwing the Shivan fleets into disarray. The Shivan fleets decided independently that finding each of the other fleets, as well as the Hive, was the top priority. All of the fleets then set out on their journeys trying to find other nearby Shivan fleets and eventually to come together.

The Ancient's Knossos devices may also have been used to stabilize Subspace Nodes damaged by the cataclysm as well as other naturally unstable nodes. The Shivans may also have had the ability to stabilize Subspace Nodes, but were not able to re-stabilize the immensely larger Supernodes.

Another side-effect of the cataclysm was the creation of "phasing" and "dependent" nodes. Phasing subspace nodes were nodes that phased in and out of a usable condition. The nodes in FS1 that were not functional in FS2 were phasing nodes which had gone into a "dormant" stage during the events of FS2 and hence were not usable. Dependent subspace nodes are "bonded" to a stronger Jump Node or Nodes, and are directly affected by things that happen to the main Node. Known dependent nodes were the extra nodes leading to Sol other than the Delta Serpentis nodes (see Node Inconsistencies for more information). Once the main Sol-Delta Serpentis node was destroyed, the other dependent nodes bound to it were appropriately destroyed.

The Great War

A very small Shivan fleet, known as the Lucifer fleet, came into contact with the Terrans and the Vasudans. They may have attacked as an instinct, or because of the interference of the rogue Terran intelligence branch.

The Lucifer fleet was a very small fleet with only a handful of destroyers at their disposal. For this reason, they took extra measures to protect their flagship, the SD Lucifer. These measures included implementing a powerful shielding system onto the superdestroyer, as well as unique Flux Cannon weapons. The reason the entire fleet was void of the beam cannons seen on the later Shivan ships is because they had never been developed. Because all of the Shivans were separated for tens of thousands of years, each developed in their own unique direction. However, certain ships remained in use, such as the Lilith, Cain and Demon, while others were phased out in certain fleets, like the Scorpion.

However, despite their measures, the GTA and the PVN was able to destroy the Shivan's flagship and the entire fleet.

The Sathanes

Before the cataclysm, the Sathanes used to nuke stars and other large objects of immense gravitational mass to create artificial Supernodes to travel large distances. The Sathanas fleet was also one of the largest fleets, and possibly the most technologically advanced.

After the cataclysm, the Sathanas fleet developed advanced devices to locate and communicate with other stranded Shivan fleets - The Shivan Comm Nodes encountered by the SOC in the second loop were just that - Shivan Communication Nodes.

The Sathanas fleet found the Lucifer fleet via the use of these devices, and decided to go into that part of the galaxy to come into contact with them. The remnants of a destroyed Lucifer fleet transmitted limited information on the enemy (the Galactic Terran Alliance and Parliamentary Vasudan Navy) and may also have transmitted the specifications of the flak gun, which may have been put to use by the Sathanas fleet themselves.

The Sathanas fleet also came into contact with a small fleet of Ravanas (such as the initial Ravana, the Beast and the Nebiros), which can explain the relatively small number of destroyers in comparison to the amount of Sathanes. The Sathanas fleet continued on to the area in which they located the Lucifer. However, there they encountered the enemy that had devastated the Lucifer fleet, and decided to fight back. Meanwhile, Admiral Bosch had learned of the Shivan's predicament, as well as the locations of many Shivan fleets, and decided to try and aid the Shivans by talking with them and disclosing the whereabouts of the Shivan fleets. When he finally came in contact with them, the Shivans changed their plans and begun bringing in the bulk of their Sathanas for a superjump. The Shivan Comm Nodes at the binary system in Into the Lion's Den were being used to communicate with the Shivan fleet that Bosch had told them of. The Shivans amassed their Sathanes near the Capella star and got ready for a superjump, and met with the Shivans on the other side of the galaxy.