Back from lunch with a random thought: instead of the clichéd human who was cursed with immortality at one set age, why not curse them in a time loop? Have them spend the rest of eternity living from twelve to twenty-seven, over and over and over… So that every fifteen years they’d wake up one morning as a twelve year old and have to start everything over.
So, in a way it wouldn’t be as bad as having to be twelve forever, but in other ways it would be worse. Having to explain the sudden age drop would be interesting. Reestablishing an identity over and over… they’d either be really good at forging documentation, really good at conning people, or just have perfected the art of living outside the system. Either way, he’d be and interesting person to have hanging around.
Then again, who said it had to be a he? Now that could open a whole new kettle of fish… You’d end up with kids only a little younger than you were when the age cycled. Hmm.