Like all living things, however, Thread needed sustenance. It was highly evolved—it ate anything organic: wood or flesh, it was all the same to Thread.

The first deadly Fall of Thread caught the colonists completely unawares. They barely survived. In the aftermath they came up with a desperate plan: Having abandoned their high technology, they turned to their remaining ability in genetic engineering to create a shield against the recurrent threat. They used life-forms indigenous to Pern, six-limbed, winged, fire-lizards that were genetically modified and enhanced to produce huge, rideable fire-breathing dragons. These dragons, telepathically linked at birth to their riders, formed the mainstay of the protection of Pern. In their haste to provide protection to their new homeworld, the colonists devised many other solutions. Some were forgotten or dismissed as ineffective.

The approach of the Red Star brought not only the mindless Thread but produced tremendous additional stresses on Pern itself. The tectonically active Southern Continent heaved with volcanoes and earthquakes, providing an additional menace that proved too much for the colonists—hastily they abandoned their original settlements and moved to the smaller, stabler Northern Continent. In their haste, much was lost and much was forgotten.

Huddled in one settlement, called Fort Hold, the colonists soon discovered themselves overcrowded, particularly with the growing dragon population. So the dragons moved into their own high mountain space, which they called Fort Weyr. As time progressed and the population spread across Pern, more Holds were formed and more Weyrs were created by the dragonriders.

Given their great losses, particularly in able-bodied older folk, the people of Fort and the other Holds soon found themselves resorting to authoritarian systems under which one Lord Holder became the ultimate authority of the Hold.

The Weyrs, with their different needs, developed differently. Unable to both provide for themselves and protect the planet, the dragonriders relied upon a tithe from the Holds for their maintenance. Instead of a Lord Holder, they had a Weyrleader—the rider of whichever dragon flew the Weyr’s senior queen.

And so the two populations grew separate, distant, and somewhat intolerant of each other.

The Red Star grew fainter, Thread stopped falling. Then, after a two hundred Turn “Interval,” it returned again to rain death and destruction from the skies for another fifty-Turn “Pass.” Again, Pern relied on fragile dragon wings and their staunch riders to keep it Thread-free. And, again, the Pass ended, and a second Interval began.

Just at the beginning of the Third Pass, a new disaster struck—dragons started dying of a strange unknown disease. With his Weyr’s ranks decimated not just by injuries and losses from fighting Thread but also from the deaths caused by this new plague, Weyrleader K’lior of Fort Weyr decided upon a desperate course of action and sent his injured dragons and riders ten Turns back in time to abandoned Igen Weyr where they might heal and return in time to fight the next Threadfall.