I suggest for a story: Fish people are invading Humania and kidnapping the citizens, so you have to go save them (it ain't much, but it should probably make sense). Also, since the class animals of PL can't normally breath underwater, why not make a special dungeon where you need a quest vanity diving mask/helmet, or else your health will drain while you're in the dungeon. Also why not make quest faces? If you beat some really hard quest, you get a face with gills (blue bear face with gills, blue mage face with gills, etc)