You pose the question of power exchange.
Everyone at some point in their lives submits in some manner or another. If we didn't our world would be full of lawless inhabitants and anarchy would rule.
So would a Dominant who wishes to protect their loved one submit in some manner? Most assuredly this is the case. If the Dominant provides even a sliver of after care, it is a form of submitting to the needs of the submissive. That however doesn't make them submissive, or even slave. It makes them passionate, caring and protective.
What makes someone a submissive, slave or bottom is all mindset. How do the view themselves? The answer to the question is always individual to the person, and the definition that results guides them in their life. If it's answered honestly.