Ah yes, gray as a neutral. Love it. The black/white contrast is just too drastic, but gray instead? Solid. A big, comfy gray cashmere (or acrylic for vegans) sweater with some black leggings is where my mind first goes, but there are numerous style options to lighten up the dark abyss that is a solid black wardrobe:

One of my favorite uses of gray is to make a rather dramatic evening outfit more daytime or casual. For example, a gray scarf with a black dress. There is this myth that to be goth you should only wear black, but I refuse this theory. Yes, the dark and macabre are enticing to us, but living in complete black isn’t the only way to express yourself as sinister and mysterious. Some examples:
Also, that whole “graphic tee under an open cardi with jeans” that Robert’s got going on is pretty much my casual state of being.