Honestly, my first instinct is to say that this person in your dreams is an aspect of yourself manifesting itself in your dreams, rather than an identity as such. Maybe your determination, your strength, your will.
It may well be a coping mechanism, however I suspect it may also be a part of you asserting itself through your dreams. The part of you which refuses to quit. In our dreams, we are susceptible to every part of ourselves. And for every negative thing you feel about yourself, there is also a positive aspect to yourself. I wonder if the traits this person represents are not those you want for yourself. The way you feel you would be were you able to fully express yourself.