- She’s the mother of the undisputed heir to Jon Arryn, so loyalty to House Arryn runs through her.
- She’s the Regent of the Vale, so the Vale’s rigid adherence to honor means obedience even if you disagree with the Regent’s actions (such as the desire to send out knights either to repress the mountain clans or to fight for Robb).
- She’s a widow with a widow’s use-rights and ambitious Vale lords want to marry her.