A lotta people presume their BPD lover is/was "addictive," but it's an erroneous assumption. The need for intense stimulation (either positive OR negative) is what keeps people returning to a high-conflict relationship, and feeling emotionally hooked.
Growing up with strive/struggle in the home of origin, sets us up for adrenaline addiction. Chaos and drama FEED that addiction (think fight or flight here), and help us circumvent calm and serenity that put us in touch with inner emptiness or sadness.
This factor makes us wholly DEPENDENT on another to invigorate our emotions (light OR dark), and give us a sense of 'aliveness' we crave, but can't manufacture for ourselves. In a sense, we believe the other person is the KEEPER of our pleasure and pain.
It's a mistake to think of anyone as "addictive." That person is merely the catalyst that forces us to FEEL emotions we've been dissociated from lifelong.
Feeling work is healing work. When we are taught to experience our emotions in the body and NOT analyze them in the head by attaching meaning and reasons to them for endless hours at a time, we begin to develop emotionally (which works for healing Borderlines, incidentally!).
The process of re-associating the client with long-buried feelings they had to surrender in childhood in order to surmount their pain, is what spawns emotional development, which is the precursor to MORAL development and its natural outgrowth, Empathy.