Long shot:
One of the three characters, I'm going with Terra since he's my favorite, ends up in Beast's Castle, at the time know by some other name, where he meets the Prince. Princy acts stuck up and sends Terra away just as the witch reaches the castle, before Terra can leave through whateve mean they may have in BBS, he hears the Prince's scream, goes back to check and finds that princy has been turned into Beast. Beast is enraged and attacks Terra, small semi-boss battle, Terra wins and forces Beast to calm down. Before Terra leaves, he makes some ominous statatemen, actually a guess, about what he needs to do to turn back to normal
One of the three characters, I'm going with Terra since he's my favorite, ends up in Beast's Castle, at the time know by some other name, where he meets the Prince. Princy acts stuck up and sends Terra away just as the witch reaches the castle, before Terra can leave through whateve mean they may have in BBS, he hears the Prince's scream, goes back to check and finds that princy has been turned into Beast. Beast is enraged and attacks Terra, small semi-boss battle, Terra wins and forces Beast to calm down. Before Terra leaves, he makes some ominous statatemen, actually a guess, about what he needs to do to turn back to normal