When we finally figured out how to perform a head transplant, we figured we'd be using it to save lives, for example if someone was paralysed from the neck down, and there was a body available after someone had sadly passed away, we could move the head to that body. And to start with, that's how it worked. We saved so many lives!
Then the tech ended up on the black market, and that's when people like Jackson here ended up getting roped in. He was an athlete, but wanted a new, bigger body, without training, so he signed up to one that would offer hi ma great body. Unfortunately for him, Sarah also signed up, she'd always wanted to be a man, and had a little more money, so got to choose hers. She chose Jacksons. So they got matched.
Jackson didn't seem too upset however, and... neither did his friends...
Even if they couldn't look him in the face...