I think that her dressing like a schoolgirl gives the illusion that Serah is a lot younger than she is, and that combines with the height difference to give this ebophile(?) vibe.

I mean, the height / size difference is pretty comparable to Buffy / Angel, which is my go-to height-difference couple. ...and lololol age difference. BUT HE'S *SUPPOSED* TO ONLY BE TWO YEARS OLDER THAN HER, PHYSICALLY.