Ice Queen
Perhaps she could have been an assistant for him back in the day, since she seems a little younger? Fai's biggest thing was his hair (he was the youngest on the team) but he had several other experiments with plants--even traveled the four isles to collect seeds from all their plants! Maybe something to do with that, since she's interested in plants and minipets?
Yea that could work. Since she's a pretty fail Alchemist even now she'd have prolly ended up messing up quite a lot . >3>