Oh, dear heavens. Still racking my brains as to who it could be, both in terms of the person described here and where Our Heroes are going, but since there's certainly King of Fighters characters canon in this world...well, crazy super-secret cultists is something that game series has. In spades. Street Fighter 5 does, too, though I haven't had any indication Gryphon has played or even seen it. Kolin (aka Helen) could fit.

Of course, they could be totally unrelated. We'll find out! And I'll keep racking my brain. These are games I know something about, dangit. =)

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Fearless creatures, we all learn to fight the Reaper
Can't defeat Her, so instead I'll have to be Her