The Maestro.
They are, to put it simply, some kind of merge of Monokuma, Alastor and Bill Cipher. (Same kind of energy.)
They're not exactly antagonistic, but they aren't really what would be considered as, to some people, "nice."
They LOVE teasing others, and often in the darkest and most crude way as possible. They can also just let two people together in the same room and let them start and aggravate their own dramas while they watch the whole thing happening from afar.
(They may cause realities to rift by doing so.)
They exist for entertaintment.
The readers need sustenance, so they will find ways to satiate it.
They think "What if this happen?" and then "Let's do it then!".
No one actually know what they think, how they think and how their whole scheme works.
The Maestro: Everything has a reason. But you can't reason everything.
And here they are @murkymusito.