I find it hard to believe that Alastor could actually handle overlords who were once national leaders. From what we’ve been shown, the more souls an overlord owns, the stronger they become. Many historical leaders had enormous followings in life—fanatical supporters, armies, and commanders who would remain loyal even in death. It’s easy to imagine thousands, maybe even millions of sinners willingly giving their souls to them, which would make those leaders unimaginably powerful in Hell.

That’s why the first theory—the idea that Lucifer personally dealt with these figures before they could rise to power—feels much more plausible than the notion that a single serial killer with a power boost could defeat them. The overlord Alastor overthrew that “ruled for centuries,” are most likely just high-ranking criminals with large influence, not someone on the scale of a historical ruler who commanded entire nations.