This is basically Wormwood from The Screwtape Letters. This whole series would have benefitted greatly from Vivzie actually studying C.S. Lewis. Nobody else has done demons better in a work of fiction, odd considering that he was a devout Christian, and despite not being Catholic, writes like one (that is a compliment if coming from me). Or maybe not so odd.
Lewis hung around with Catholics like JRR Tolkien (who was disappointed when he became an Anglican) and was greatly influenced by Catholic writers like GK Chesterton, so it's not so surprising that he knew how to write like one. He was also a great fan of mythology and occultism as a young man and studied Norse, Greek, and Celtic mythology and the Icelandic sagas, all of which no doubt had some effect on his writing later in life.
I'm actually glad you brought him up, because Lewis is a really good illustration of the problem with so many modern-day creatives and why so many of them seem to pale in comparison with people like him. Lewis was a very smart man with a vivid imagination who was incredibly well-read and intellectually curious. He also had a life full of experiences, both positive and negative, that went on to influence him as a writer, person, and theologian. His mother died when he was a kid and he was left with a distant and demanding father and got shuttled around to various schools and tutors. He served in WWI as an infantry officer, lost several friends, and was nearly killed himself by an errant artillery shell. One of his friends who died had asked him to look after his mother if he was killed, and Lewis took this request so seriously that he went to live with her and spent the rest of her life taking care of her. He rejected his Christian faith as a teenager and spent a long time, as he put it, being "very angry with God for not existing" and "equally angry with him for creating a world." He ultimately returned to Christianity after years of atheism thanks to the influence of his friends Tolkien and Hugo Dyson and wound up becoming one of the foremost lay theologians the Church of England ever produced. All throughout his academic career, he worked with and taught many very smart people, and his friends in the Inklings, including Tolkien, Owen Barfield, and Charles Williams, helped him refine the Space Trilogy and the Narnia series. They also occasionally did competitions where they read aloud from the books of legendarily shitty author Amanda McKittrick Ros to see who could read her drivel the longest without laughing, so sitting around and mocking no-talent lolcows over a beer is a grand and honorable tradition that we should all be proud of.
Vivzie has not lived anything like this kind of life. She's gone from Christian to atheist and her parents are divorced, but those things happen all the time and don't seem to have had a major impact on her. She has had no great tragedies, no struggles, no friends to challenge her beliefs or help her refine her work. She can't take criticism, she doesn't seem to want to do any kind of research beyond the most basic background stuff, and she is incapable of stepping outside her own perspective to look at the world through someone else's eyes. She's certainly not alone in this among current-day creatives, but she's a good example of the problem with them. William Faulkner once said that "A writer needs three things, experience, observation, and imagination, any two of which, at times any one of which, can supply the lack of the others." Vivzie clearly has an imagination, damaged as it is by a steady diet of Tumblr bullshit and low-denominator pop culture, but she has no experiences or observational skills worth a damn and all of her creative output demonstrates that fact. She has the skeletons of interesting and provocative stories in HH and HB, but she's buried them under a sloppy, rancid pile of Tumblrina-level drama, pointless edginess, and yaoi-fangirl shipping, because that's all she knows how to write and she's never going to be able to evolve beyond that without some major changes to her perspective and patterns of thought.