Her relationship with the proto-Ishgardians seems to be the closest of the three wyrms, given the reclusive nature of Hraesvelgr and the apparent mistrust of Nidhogg before the betrayal; I think her base is also the closest to the landlord colony.
Great wyrms are also rather powerful entities, so it is highly likely that King Thordan used her trust of the mortal races to ambush her. I highly doubt that the proto-Ishgardians would have been able to subdue and devour her eyes so easily without some degree of interference from her or her brothers broods; for the betrayal to work, it would require some degree of compliance (or trust) from Ratatoskr; it is likely that they requested a secret meeting or learned from her when she would be most vulnerable, before betraying her.
