Red velvet cake is a buttermilk cake, not really a chocolate cake. It has a little cocoa in it, but not enough to give it a chocolate flavor. The buttermilk is what gives it the distinctive flavor, which I can't even describe because it's unlike any other kind of cake. If you make it from a boxed mix it will probably have powdered buttermilk in it, which doesn't really give the same result as real buttermilk. It just won't be 100% "right."
However, even if you make it from scratch it might be a little "wrong" for one reason. The red color.
My assumption is that when red velvet cake was invented, whenever that was, they used a non-alkalized cocoa, which would have given the cake a reddish color. But only slightly red. (If someone knows something I don't and I'm wrong about this, feel free to correct me. I'm curious about it, actually.)
The way that you get the red color these days is to add an obscene amount of food coloring to the batter. The recipe that I use calls for two tablespoons of red food coloring. If I double the recipe that would be 4 Tbsp, which is a quarter cup of food coloring. That's a lot.
I tend to add less than I'm supposed to because this just seems more than a little nasty to me. You could, theoretically, make a blue velvet or a green velvet cake, it's not really anything other than the food coloring that gives it the color.
On the other hand, you could get the same flavor to the cake without adding any color at all. If you like the flavor but want to avoid the dyes, just have the cake made without the color. I'd be happy to do that, and I wouldn't even get creeped out when I mix the batter. Much nicer...