Impossibly tiny, strange pieces of Genesis and Bereave, scattered amongst the Timelines when the Main Timeline was born. They awoke, slowly, to a strange new world, each Timeline unique, some born into voidless chasms, some finding fellow Fragments, others completely alone. And collectively, they realized, 'this world is special. I have to protect it.'
So they set out, as individuals and groups, fighting and skirmishing and agreeing and allying and politicking. As time wore on, several enormous umbrella factions emerged, consolidating great numbers of them under certain banners. The largest of these is the Coalition of Reality, dedicated to the preservation and categorization of Timelines.
But there are as many factions as there are individuals, and infinite nuance between even that. Conflicts brew and churn, spurred on by the inevitabile arguments that arise with the protection of billions.