In response to discussion of an overarching storyline, I came up with a potential idea. Essentially, after existing for about 100-350 years, the IVC, once an anchor of stability in the interversal political sea, has become an oppressive, bureaucratic dictatorship. It maintains near-complete control over a number of universes, breaking the policy of non-interference and neutrality to the point of contaminating several timelines, all to satisfy their own selfish needs. And it's members have been genetically engineered and given cyborg implants to the point where they have become a new species - Homo superior, or whatever else we want to call them. Essentially, they are racist, oppressive, tyrannical, greedy and corrupt, rotten to the core.
As a result, a number of IVC bases, located mainly in the Crossroads and Romanum universes, end up rebelling against the IVC's rule. A complex web of alliances turns this into a conflict spanning multiple universes and embroiling hundreds of countries and factions. It's essentially the two (or more) world wars crossed with the Last Great Time War. By the end, the IVC has been destroyed, but countless universes have been contaminated, Crossroads is in ruins and relatively stable wormholes have been left all over the place (similar to Stone Rings), allowing people to travel between universes with relatively low levels of tech.
Any thoughts, opinions and/or suggestions? Remember, it's a first draft.