So question about metering
I know meters are tuned for midtones and thus, something darker than midtone will reflect less light and lead to overexposure and vice versa and you thus compensate accordingly

I also know that according to Zone system techniques, that you can place highlights in approx +2 for slide (meter highlights and open 2 stops) and the darkest part you want details in (shadows) in -2 (meter shadows and close down 2)

But what happens if that highlight is dark toned (if that makes sense? i.e. black detail being rim or edge lit)