So, let's take as a given the following -- I recognize that these are all contentious points, based entirely on speculation, but I just want to toss this out there.
This is not a theory I believe in with all my heart; I merely present it for the sake of entertainment.
Abstract, for those too lazy to read: the destruction of the Lucifer crippled the Shivans' strategic command-and-control abilities, and their actions in FS2 were, as a result, confused and ineffectual. The final destruction of Capella was a call for help across galactic distances, using a supernova as as beacon.
Speculative premises, then:
1. The Sathanas is a relatively combat-ineffective juggernaught design. It is not a warship to the Shivans, but a specialized effector for certain applications of their subspace technology -- perhaps including the opening of jump nodes and the destruction of stars. It has tactical value, but it is not a main-line warship.
2. The destruction of Capella by the Sathanas fleet was one of two things: first, the generation of a supernode (this is a common theory) or, second, a signal. I hypothesize, without real evidence, that the Shivans sacrificed multiple vessels in an attempt to touch off a supernova as a signal to distant allies -- extragalactic Shivans. Capella was chosen as the target over Gamma Draconis, but why I do not know -- perhaps properties of the star, or perhaps because of the potential for collateral damage.
I would like to advance the idea of the FS2 Shivans as a confused and leaderless force.
At no point in FS2 do the Shivans exhibit the ruthless, unstoppable goal-seeking behavior of the Shivans in FS1. They appear to have lost their offensive momentum. I posit that the destruction of the Lucifer beheaded the leadership of the Shivan collective.
We see at the end of FS1 that the destruction of the Lucifer leaves the Shivan fleets confused and helpless. It may be that the Lucifer was a unique vessel that served as the 'queen' of Shivan forces in the local area or in the galaxy at large. This kind of centralized intelligence is a common cliche in science fiction, and it rarely has a good explanation. I suggest that the Lucifer itself might be a post-singularity AI of some kind -- a 'Power', for those here who read Vernor Vinge -- and that its mission requirements prevent it from granting similar intellect to its subordinates.
The Lucifer spearheaded the Shivan attempt to exterminate the Terran and Vasudan species, possibly because the Shivans knew that this area of space had once hosted the Ancients -- a powerful and dangerous race that had come very near to uncovering weaknesses in Shivan technology.
The destruction of the Lucifer left the Shivan collective in chaos. After years of rebuilding the Shivans achieved a kind of order, but when the Knossos at Gamma Draconis opened, they were only able to perform an ineffectual sortie to secure their new beachhead -- a single cruiser and a group of transports. (In fact, based on a CBanim before 'The Lion at the Door', there may have been a Ravana on station at one point which then departed back to the nebula.)
The technological progress of the GTVA forces might have been easily countered by the Shivans under ordinary circumstances, but as it was, the Shivans were only able to act effectively on the defensive: deploying successively larger and larger vessels to attack GTVA warships, only to lose them to fighter strikes. At last they resorted to the deployment of one of their Sathani, in the same system-sterilizing role as the Lucifer -- only to find that the GTVA had a match for that as well.
In the end, with their first Sathanas sortie destroyed, the Shivans found themselves with the raw firepower necessary to destroy the GTVA but none of the requisite tactical acumen. They seem to have lost the capability to use transient or hidden nodes to outflank GTVA forces -- the only canon explanation for the 'skipping' behavior of Shivan attacks in FS1.
Hampered by the bulk of their own war machine and the absence of any firm guiding will, the Shivans called for help, activating a supernova messenger contingency to signal other Shivan groups throughout the local universe.
This might lead to :V:'s hints that FS3 would contain an 'even bigger problem' and vessels as large as planetary bodies.
There have been other theories I've read which suggested that the Shivans overestimated the capabilities of the GTVA by a considerable margin. I would like to give credit where it's due.
I am not a strong believer in this theory -- I like the idea of the Shivans as inexplicable and unstoppable destroyers -- but I do think it's an interesting one to consider.
Thoughts?