Hogwarts is doomed (a harry potter/helluva boss crossover)

Trouble

Harry woke up quickly. For a moment, he thought that he was still in the cupboard under the stairs, but after a look around the room, he remembered! He was in the tower of Lust
(he wasn't quite sure what Lust meant, but seeing as Ozzie was the Deadly Sin of it, he supposed it must be good.)
And he was now a demon! Just to confirm, he reached up to his head and felt his new deer ears and then his antlers.
He grinned, feeling his new sharp teeth even as he did so. He couldn't wait to show everyone! Especially Alastor, after all, he had been the one who removed the magic in his scar.

Then he paused, thinking. He was apparently a wizard and a demon as well. Surely, there would be a way for him to get to the hotel place where Alastor resided? It would be a lot easier for Ozzie if he didn't have to take him everywhere..

Making up his mind, he jumped out of bed and sat down on the floor. He hummed. He didn't want Alastor here, but he wanted to see the Radio Demon. Therefore, he had to go to him! Now, how to go about doing that... If he went like this.... or like that....

Suddenly, there was a loud pop and a flash of vibrant green light, and Harry vanished.

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One second later, in the lounge of the Hazbin Hotel.
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There was a loud bang and a flash of green light, startling the inhabitants of the hotel.

"Fuck! The hell was that?" Angel Dust cried, looking across the room in shock.

A small deer demon was sat on the floor looking slightly confused.  He had bright  neon blue hair and wide green eyes. He looked quickly around the room before jumping up excitedly.
"Alastor!"

Angel's eyes swivelled to the Demon in question. Alastor looked quite shocked, although the permanent smile hadn't left his face. That ruled out this... child.. being his then, however, said kid was wearing a jagged cape-cloak-skirt thing which,  aside from its colours,  looked extremely familiar...

"Hey Al, you didn't say you had a kid" he drawled teasingly.

At once a ferocious glare was leveled at him before turning to the child.

"Have we met?" Alastor enquired, looking at the small demon curiously.  That blue hair reminded him of someone.... but who?

"I'm Harry, silly! I mean I do look different.."

Well, well, well. Wasn't this interesting.  The, decidedly human, boy from yesterday, Harry Potter unless he remembered incorrectly,  was now, very much, a Demon. There was only one way to do that, well only one that didn't involve the death of the human in question.

"Asmodeus made you his Chosen?" He enquired, letting the radio edge slip into his voice ever so slightly.

"Yep! It was really fun, we got to draw cool squiggles and patterns." Harry chirped.

"Hold on, first, what in Hell is a 'Chosen' and second, who in Hell are you?" The spider demon interrupted part curiously,  part angrily.

"Well,  a Chosen is a human turned demon by one of the Deadly Sins, in Harry's case, Asmodeus.  They are essentially on the same level as Charlie, if not higher." Alastor responded.

"And I'm Harry! Nice to meet you!" Harry added.

"Er.. Nice to meet you too I guess? I'm Angel Dust, call me Angel."

"Now that we all know each other, Harry, may I enquire how, precisely,  you arrived here?" The Overlord asked, curious at how a young human-turned-demon could have got in here without a portal.

"I don't know."

Shaking his head to clear any static, Alastor stated, "You... don't know."

"Yep! I wanted to see you cos I'm a demon now, and then there was a bang, and I was here!" Harry grinned happily, pointed teeth on clear display.