Typing this down as fast as possible before it exits my brain so you'll have to work with me here
so integer underflow is a thing where a computer number, if it goes low enough, will wrap back around to the highest possible number
this hypothesis/theory/??? thinks that something becoming darker than dark means it wraps around to the maximum possible amount of light
This could explain why determination creates dark fountains if determination = light (either by adding so much light it reaches the maximum, creating a "dark" world, or that it adds so much light it overflows and becomes maximum dark)
This theory implies darkness is not actually darkness. does that make sense? no.