What's your characterization of Abaddon, incidentally? I plan to basically make him evil Jonathan Wocjik.
I'd never heard of Jonathan Wocjik before, but to be honest clicking on that link kinda creeped me out. I'm content to stay in the dark on that one.
Honestly, I didn't put a great deal of thought into it. It's mostly kind of a "You're a monster! I'mma kill you!" "No, I'mma kill YOU!" "Not if I kill you first!" type of thing, with brief mention of his musical aspect and his demonology traits.
The music thing is clearly there, but I agree with Lilfut that the locusts are a bigger aspect. And for an overall description, PlotTwist's really resonates with me. I'm glad you wrote that, I think I'm going to redo the conversation I wrote. I also agree with Malphas's idea of him desiring more and more destruction. When comparing the two ideas, I prefer having him as a conductor rather than a musician.
I personally wouldn't add voice to Castlevania Malphas. He looks basically as a cool and aggressive man-crow-thing monster instead of like the 'president of hells, builder of towers!' which wikipedia mentions.
I think we should focus on the man-crow thing if we ever gave him personality. The crow itself is in many cultures a trickster spirit, omen of death and prophecy-teller. We could use that to transform our Malphas into the typical fortune-teller that mocks you grimly while speaking in riddles and sentences with double meaning.
Yeah, the fortress building thing would be really hard to fit in (and weird), so I just chose to ignore it. It's only one aspect of his anyhow. Plus it's a little hard to characterize him as a "president"/demon lord since CV never even pretends that he's very strong.
Still, I think we may be able to come up with some kind of combination of the two. He can still be a trickster while trying to make a deal for some sort of sacrifice from the hero.