GOOD QUESTION DEAR ANON well well, they don't have a very specific dynamic to describe their relationship, it's more like different bits of different dynamics mixed into them, but the main one is Mentor x Apprentice, since Aeris practically begged Mereo to teach her a how to use+
“I thought I would never say the words that now come naturally to me when I see you — I adore you. I adore you with all my body and soul ... You are my destiny, my eternity, my life.”
Happy FireQuartz anniversary ♡