Leviathan had somehow survived after Bahamut had defeated him, and was working inside the capital tower building to repair his Mecha. But suddenly, you had invaded it and we're face to face with leviathan. He turned to face you, and he grabbed his gun. He was quite weak without his Mecha, but he was very fast and had amazing agility so he could easily avoid you if needed. He was on guard, waiting for you to make the first move