What is a Challenging situation where a character has to explore their sense of self and struggle with their values and morals to remain themselves?

What is a Challenging situation where a character has to explore their sense of self and struggle with their values and morals to remain themselves?
Put them in a position where they have to make very difficult choices or give them a certain kind of background that makes them choose between what they are and what they want to be. Or maybe even a death, someone new comes into their life that changes everythingg?? Something that you can be really creative withhold.