Thief seems to be the consensus for Folykl's class, but does it count as "stealing" through Void if Kuprum is willingly giving her power? I could see Mage or Witch in the "knowing" or "manipulating" senses too, though I am still thinking Thief.

I personally think she’s a Heir or a Witch, with Kuprum as her ‘familiar’. She also shares the trait of introducing her Aspect into her speech- Just as John adds breathy pauses between compound words and Jade woofs, she    adds    void between words. So yeah my headcanon for her is likely a Heir.