Hmm. Perhaps I could make one the catspaw of the conspiracy of villains, and one start to join it. He'd need to learn magic to do that -- merely regal power is not enough to make him acceptable -- though if he's of suitable caliber, perhaps one will propose teaching him.
Then, using the other as a catspaw involves groveling enough to satiate his pride, and if there's one thing they don't like, it's sacrificing their own pride for their plans. They try to push it off on each other. . . .
This plot makes the roses overgrowing Sleeping Beauty's castle look simple.