The red wings got shot down. Cecil must be dreaming - going to the moon?
Bartz gets hit by a meteor. After spending so much time chained to his boring village, his response is to create a grand fantasy reaffirming his importance as a warrior of light.
Terra was killed by Quezacotl at Narshe. The rest of the game is a hallucination seeded by magitek, the artefacts of Kefka's torture, and the Magicite's presence.
Cloud got skewered by Sephiroth. The game is his own dream, finally granting him Hero status.
Squall's dead.
Zidane got his head crushed by Beatrix at the end of the first disc. Terra is his own projection, wondering where he'd come from.
Tidus was just a dream.
Reks was the real main character of XII. He couldn't internalize Gabranth's betrayal, so put together a parallel tale about his 'parallel twin' and Vaan.
Ramza was blown up at Ziekden fortress; Delita becomes his eroticized fantasy of a man who creates a better path for the nation.
Qhimm's dead; this is just a nightmare about forum life - endless iterations of borken board software, trolls, prats, spam, and crap.