When the norn sisters were first pulled into Arcadia, not many Gods from Norse mythology were pulled along with them. So during the war of Gods when the purge started to kill or capture any God who can see the future, the norn sisters became the prime target for everyone.
The Norn sisters, with their unique ability to see the past, present, and future, became the coveted prize sought after by every warring faction. Their power and knowledge made them indispensable weapons in the hands of those who could control them.
Because not only one of them can see the future, they come in a combo where one can see past and other one present. Just the thought that having these 3 in anyone's faction would give them the biggest advantage, as they can see their enemies' past to learn about their weaknesses, monitor their situation instantly no matter where they are as present, they can also change their plans and strategize after seeing the future.
