Maybe one that has a body swap element to it perhaps could be an idea. An escapee stalker with a body branded with a curse could be searching for a new body (preferably that of a leader to the stalker) to escape to in order to dodge the effects of what the curse would do, which would slowly alter their form with strength and skills diminished for the purpose of making the curse's victims easier to contain when they had taken full effect.
By the time the changes would have finished, the appearance of the victim would look almost as far from a leader as one could get, especially with the collar and other slave clothing they were supplied with. If there are other events to do with the forms, perhaps the collar would be something that could complicate things in some areas. She would have to rely heavily on her party's loyalty and protection to reach their destinations without problems.
That's one idea.. ^^"
Another form that might be good to introduce is like an imp or a lesser succubus (Not a full fledged one). To avoid similarities, she could be a sort of cranky and demanding type rather than a seductress being. Smaller wings, more slender than voluptuous, etc.
Some other idea for later could also be to introduce a new type of cursed artifacts that take even longer to activate, though affect the player instead of party members for 'Game Over' effects. Maybe they can be toggled as well in case users may not want them, but why not include the player in some sort of inanimate action as well for daring to let the artifact cross 50-100 power without selling or whatever it is? That could open up a large selection of options too. : P