Contract
Hades' contracts swam in legalese and technicalities, but at their core, they were very simple. No one entered Hadestown without permission, no one left Hadestown without permission, and once you signed your name, you were legally bound to the realm.
For as long as anyone, mortal or god, could remember, his contracts were unbreakable. Hades was ever inexorable and shied away from bending his own rules, with no exceptions given. The red ink, so much like blood, that his workers signed in only added to their effect.
Persephone's feelings on the contracts were mixed, and she worked to bend the smaller issues where she could—giving lucky shades a break now and then under the Queen's orders, or arranging for transfers if a certain job suited others better.
But the most crucial parts of the contracts were all Hades' jurisdiction, which he checked thrice for loopholes.
It had never bothered her until Hadestown had begun to change for the worse.