Crowley is the twst version of the phantom blot, and that's bad news somehow.
Before I start my schizophrenic ramblings, I'd like to first make clear who the phantom blot is. According to the wiki itself: "The Phantom Blot is a masked villain who first appeared in the comic strip Mickey Mouse Outwits the Phantom Blot by Floyd Gottfredson, which was published in the form of daily strips from May 20 to September 9, 1939. Draped in a black cloak that conceals his true identity, the Blot is a notorious criminal whose aesthetic takes inspiration from inkblots. The character serves as one of Mickey Mouse's archenemies, with schemes ranging from crooked theft, to world domination." "The Blot is very vain and his desire for money and power is only surpassed by his desire to immortalize his name in "the annals of crime"; although he often desires wealth and power, his greatest lust is for fame. Some of his plans have no monetary gain for him, but their purpose is to spread fear of him to the public, adding to his reputation. He seems to do evil schemes simply to be evil, and to spread his reputation as a villain."
Crowley shares many design similarities with the phantom blot, the most notable being his weird shiny eyes under that odd mask. The phantom blot is described as vengeful, cunning and just evil all around. Curiously, he has bouts of empathy which he says happen because he has "such a soft heart". How true that is is up to debate, considering that he is listed as having a black heart. In another iteration, the phantom blot acts somewhat like a witch hunter and wishes to rid the world of magic. You can see the similarities in design below. Yes, I am aware Crowley is mostly based off the evil queen's crow. However, most twst characters are based on more than one singular thing. Yana has a thing for mixing stories to weave her tales in a more interesting manner.
We get many more hints to Crowley's true nature in chapter 6. Idia brings up how Phantoms act like some sort of parasite, sucking their hosts dry until they poof. After the host dies, the phantom can roam around mostly as mindless monsters, though the more powerful phantoms (like Ortho) seem to have full conscience and be able to speak. One other thing that caught my attention was how it was mentioned that some phantoms disguise themselves as dire beasts, and we do have a character that is deadass called Dire Crowley in this. Surprisingly, it is in the school of this Dire Crowley that people keep overblotting with no explanation. And it is this same Dire Crowley who keeps trying to keep this under the covers. Not for the school's sake, but for his own. Crowley is not a man. Crowley is not Levan. Crowley is possibly the phantom left behind when Levan overbloted. He is the one making the students overblot for a reason, and he is keeping Yuu stuck for possibly the same reason. What he could want is still up for debate, but I'm sure this old man will be the final twist villain.