A step-father, step-mother, step-daughter, or step-son.
One thing we all agree on is that people are generally assholes. Some are just cruel assholes, some are spiteful assholes, and some are assholes because they are hurting inside.
The worst thing about being a step-child is having yet another authority figure in your life when you already feel that the two you were born with have let you down.
The worst thing about being a step-parent is having to care for a potentially hostile, emotionally damaged child who resents your mere presence.
Providing that neither the step-child or step-parent is 100% asshole, a bit of tolerance and mutual respect can often make for a really great relationship.
Things to remember -
"Your step child probably doesn't really hate you, they're just angry at life - and probably with good reason."
"Your step-parent probably isn't as big an asshole you make them out to be. They're never perfect because they're human - just like you."
A step-person can become a very valuable person in your life and much of that is often a choice you make yourself.