‘Freedom’ is a highly ambiguous and disputed concept, but in at least one sense it is the opposite of ‘slavery’, so investigating this negative side may be illuminating.
Slavery seems to be one of those concepts that, in its paradigm case, contains a cluster of several elements, and which is applied to other cases that share some of those elements, so that those cases need not share any one single element with each other.
Here are three ways in which a relationship might ‘subordinate’ one partner to the other:
1. Firstly, it might deprive them of long-term executive control, in that long-term decisions about the relationship, and any costs or benefits it includes, aren’t made by them. The key form of this, of course, is not being able to control whether one enters or leaves the relationship itself.
2. Secondly, it might deprive them of short-term executive control, in that day-to-day decisions that involve both participants are made primarily by the other. This is what most corresponds, I think, to the idea of a ‘hierarchical’ structure: hour-by-hour, minute-by-minute, one person commands and the other obeys.
3. Thirdly, it might frustrate their desires, while satisfying the desires of the other person – independently of who makes the decision. This could be thought of in terms of ‘psychological predictiveness’: if you take the things that the participants do together, and you know all the psychological facts about what one of them likes, enjoys, desires, or otherwise feels certain ways about, can you explain the former in terms of the latter? Or more precisely, does one person’s psychological profile better predict what they do than the other’s?
The strong emotional charge of ‘slavery’, I think, comes from its combining all of these ways of dominating someone. If I am someone’s slave, then I am so involuntarily (whereas they can sell me), I must obey their day-to-day instructions, and my activities are all directed towards satisfying their interests, not mine.
But they don’t always coincide like that. For example, it seems to be characteristic of ‘caring for’ someone else that you ‘subordinate’ yourself in the third sense, guiding your actions by the needs and feelings of someone else, and putting these before your own. But the carer may well still be ‘in charge’ in that they are the one who makes the decisions.
Assuming that one particular form is to be absolutised, and that when it is absent there must be total freedom and when it is present there is always some measure of ‘slavery’, is, like most such rigidly simplistic readings of important concepts, characteristic of right-libertarianism, for which nothing happening within someone’s job can be anything but purely free (because people take jobs ‘voluntarily’), while any taxation by the state is ‘a form of forced labour’ (because not thus ‘voluntary’).
In fact, though, one can find any combination of these forms. Personal servants are ‘enslaved’ in senses 2 and 3, but ‘free’ in sense 1; a woman denied an abortion but determined to look after the child well is ‘free’ in sense 2 but ‘enslaved’ in senses 1 and 3, while their child is ‘free’ in sense 3 but ‘enslaved’ in senses 1 and 2.
Anyway, those are just some observations.