Another example would be Orphan. in FF13, you are fighting Barthandalus throughout the game, but he again takes a sidestep to Orphan, who to my understanding appeared out of nowhere.
Orphan was not completely out of nowhere. In one of his pre-battle speeches (either Chapter 9 or Chapter 11), Barthandelus drops Orphan's name and a couple other bits of info.
So even if Orphan is unexpected, he wasn't completely and totally out of nowhere.
Newer FF player. Learning the ropes. Game in sig is what I plan on playing when the italicized games are finished.
My Checklist (Italics = now playing, Bold = beaten): I, II, III, IV, V, VI, VII, VIII, IX, X, XII, XIII