In the classic cases of co-dependency, there is a one-sided relationship which enables one party to keep up their addictive or other destructive behaviour, whatever it may be.
Which has always raised a question in my mind of what do addicts and non-addicts see in each other anyway? Would it not make so much more sense for, say, two alcoholics to meet and to fall in love and to proceed to drink themselves to death in a manner of their choosing?
Would that not at least simplify matters to some extent?
I know it sounds like something out of a Tom Waits song, and perhaps only Tom's voice and sensibility can do justice to the nature of such a tragedy, which has at its centre this very strange thing: for some reason, that seemingly ideal combination doesn't seem to work too well.
For a start, a lot of alcoholics lack the self-knowledge to be aware that they are actually alcoholics, which prevents the kind of clarity you need in such a doomed arrangement - one partner may be resigned to the inevitability of self-destruction, while the other clings to the illusion that they're not like that, they're just going through a bad spell, or something.
Rarely do you find that dual commitment to just go for it, that meeting of minds with the joint purpose of total alcoholic annihilation. I mean, it would seem logical that you're better off with another alcoholic all round, since it removes one of the great obstacles in the lifestyle of the addict - the fact that their partner is being damaged by this behaviour and is, understandably, annoyed about it.
After all, if you happen to be in a relationship with a fellow alcoholic, any damage you are doing to them is easily matched by the damage they are doing to themselves. So it should be like a treaty of mutually assured destruction to which both parties have signed up voluntarily, even deliriously.
Yet its relative rarity is probably down to a deeper problem in the nature of these things - it is very hard to love another person, even another alcoholic, when what you love most of all is the substance to which you are both addicted.
Again I would allude to the title of this column, which emphasises the fact that addiction consumes the victim with feelings of obsession akin to love, but eventually with all the good things about love taken out - and so, instead of our two alcoholics being devoted to one another, they are more like old mates, each of whom is observing the devotion which the other has for the drink.
Some essential element is missing from the chemistry, it's all yin and no yang.
Which means it is more likely that an alcoholic will end up with a 'normal' person, with co-dependent tendencies. Maybe each of them sees something in the other that they feel is lacking in themselves - perhaps the co-dependent one would like to have some of the spontaneity of the other party. The good spontaneity - at least until the bad stuff gets going.
So there is this powerful attraction, this sense that somehow a better kind of unity will emerge from these deficiencies which they perceive in their own personalities.
But in truth, it usually doesn't grow into something greater, it degenerates into something less than the sum of its parts.
"I wanted something that they had," is the kind of thing that a person in a co-dependent relationship is likely to say, after the event.
But it is also a line that you start to understand better, if you're an addict who is getting into recovery and has found one of the fellowships - you wanted something that somebody else had, you were just looking in the wrong place. At the wrong person.