Aristotle holds that substances (such as you and me) are ontologically independent from nonsubstances (such as our qualities and quantities) but nonsubstances are ontologically dependent on substances. There is then an asymmetry between substances and nonsubstances with respect to ontological dependence. Such asymmetry is widely and rightly thought to be a lynchpin of Aristotelian metaphysics. What is really real for Aristotle are such ordinary objects as you and me. Our properties - my paleness, your generosity - inhabit Aristotle's ontology only in so far as they are ours. This much we can all agree on; and I'll only briefly rehearse one of the reasons for ascribing this picture to Aristotle below. For I agree with the orthodoxy that substances enjoy a certain kind of ontological dependence from nonsubstances - an independence which nonsubstances lack with respect to substances. But I disagree with the orthodoxy as to what kind of ontological independence substances have and nonsubstances lack. Under the orthodox interpretation, the ontological independence ascribed to substances and denied of nonsubstances is a capacity for separate existence. But, I'll argue, there's a tension between substances and nonsubstances with respect to ontological independence.
Corkum, Phil, "Ontological Independence in Aristotle's Categories" (2003). The Society for Ancient Greek Philosophy Newsletter. 387.