I have a theory
Though purely unintentional, Sayori and Sephiroth appear to made for each other and each other alone. I have a few reasons for it:
Similarities
-Both of their names start with the letter S
-Both of their names have 3 syllables
-The number of letters in each of their names are multiples of 3 (Sephiroth having 9 and Sayori having 6)
-Both of their names have an o, an r, and an i along with an s
-Sayori leaves her blazer unbuttoned, just as Sephiroth leaves most of his coat unbuttoned
-Despite their outer appearances, both have their own inner turmoils
-Both are linked to the ocean in one or more ways. Sephiroth’s appearance in the original game was based off the shark from Jaws, and sayori (Hyporhamphus sajori) is a type of fish known as the Japanese halfbeak
-Both have blue eyes, though Sephiroth’s eye color is closer to a greenish color
Differences/Complements
-Sayori has short coral pink hair, and Sephiroth has long silver white hair
-The warmer shade of Sayori’s hair could reflect Sayori’s warm personality, compared to the close to cooler shade of Sephiroth’s hair which could reflect his cold and bitter demeanor
-Sayori is a short female and Sephiroth is a tall male
-Factoid: Sayori is 18 and Sephiroth is 27, which makes Sephiroth approximately 9 years older than Sayori