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Nightmare Fuel: The Megas
The fact that Dr. Light is singing I Want To Be The One To Watch You Die.
Afraid of the Dark is about Shadow Man consciously losing his former personality to darkness after Dr. Wily repairs and reprograms him—and he's terrified. At around 3 and a half minutes in, the darkness sings to him.
The Haystack Principle gets nightmarish when Needle Man starts singing about how much he loathes and fears his new body, while another voice repeatedly confirms that this is who he is.
The prelude to "I'm Not the Breakman", called simply "The Red Song", can be this without much context for it. It's a wordless audio track of Mega Man running to the site he'll meet the mysterious Break Man. And then he hears something in the distance, beyond the churning machinery. A song, sounding as if it's being played on a chime. A machine explodes as the blue hero's opponent teleports in, Break Man's systems powering up as a raging fire can be heard.