Imagine if the X-mansion wasn't under constant attack. Some people have powers and they are invited to live and study at the institute. There are instructors present as well as an on-site lab where their abilities are monitored. Whether your character's ability has caused them anguish or is more of an incidental thing (like having pink hair or enjoying pineapple on your pizza) is up to you. And honestly, you're welcome to play someone without a power so long as they have a reason to interact with everyone. Mack here is a regular ol' security guard on campus.