Is Zero...special?

[kaynide]

From talking to her in her garden, I get the impression that she's not a voidsent at all, but a descendant of the Mhachi.

Very possible as well- not sure as she refers to Gruff as a child and seems to exert a degree of power over them.
Powerful voidsent? Descendent/controller of voidsent contracts? Benevolent lich?

Shame it’s relegated to a minor seasonal event as it has lots of potential.

Something bugs me about Zero if she can revert back to her normal self through Aether then why has this not happened with past voidsent? I don't think there was any lore eluding to that.

Zero is technically 1/2 voidsent and was essentially birthed human with void corruption. We aren’t sure if the other voidsent are entirely new entities, corrupted people or if they even have an uncorrupted form.

[Rannie]

Scarmiglione and Barbariccia were once humans
Corrupted by the darkness like Sin Eaters were by light. Atleast that's what it seemed like in that one side quest with the multi eyes voidsent... the only difference it seems between them and Zero possible is she was born with the powers to turn them into crystals and have a sort of partial ward put on her due to her mother being one as well. Though that's just a guess.

Also, and I could have misinterpreted this, but didn't she say the form she had when we met her was due to Zenos?