I think that a much more surprising outcome than Hydaelyn being evil would be one in which Zodiark is good. The short story 'Ere Our Curtain Falls' outright states that Zodiark became the will of the star and averted the final days. So who was the third party that caused the final days? And if Zodiark defeated them, then why was Hydaelyn necessary at all? Why sunder and seal away an evil that you can simply defeat?