Thou we know little about this person directly we do know at least a little and can speculate.
Known
- insanely intelligent
- they are not a god or deity naturally nor do they wish to be one. (as it appears at least)
- there true name is unknown
- they have gone by many names one being Ask as we are aware of
- the created atlsia for a purpose.
- they prefer white hair
- they created everything we see in duet night abyss
Possibilities and theories
- they have been through a lot
- theres a possibility they have been corrupted by an unknown being (im almost certain this one is true)
- they created atlsia as an experiment of worlds they could create or of better ones
- there a women
- most likely not of the 4th dimension (dimensional stack not spatial dimension)
- Vita and Bors are themselves or split pieces of themselves
- they have very few people close to them
- there extremely cautious.
- there a naturally kind person, thou they can become extremely defensive or mad in certain situations.
Of course none of this is certain and should be taken with a cup of salt water.
Fluttershy
The mysterious being could be a possibility that it's either the creator or his representative that spoke to Katya, especially the three words that were used: "Mind your words!" This further raised theories
In addition, Lisbell could be related to the creator, due to her position as the Mistress of Patience (we can see that most of her stories remain unavailable), plus her consonance weapon, Samael, is based on biblical reference