Sometimes I call them salt and pepper. They are a funny pair, though they are rarely this affectionate anymore. Henry is more than twice her size, but she's the one always starting shit for some reason.
Yeah I don't think they need to have a black base to be a tortie, as far as I know. I never had pets growing up and these are my first two fur babies, so I'm not an expert.
But they definitely seem to have a unique temperament compared to other cats I have met. At least this one, lol.