LOL, nice one Velo! But in if Leviathan hadn't attacked Cecil would have been useless later on in the game because Darkness cannot beat the four fiends and the final boss (And some other enemies of course). Rydia would have still been a little girl and a crappy summoner/mage, but she would still have had white magic (albeit at a very crappy level). Palom and Parom would not have been there to save the party from Cagnazzo's trap, but they themselves would be safe as they would not have needed to turn themselves to stone. I haven't played IV in such a long time and dont remember everything about the story, so I cannot foresee what else could possibly happen.