You were adopted by the Handler and trained to be an assassin for the commission. You were sent a job by your Mother (the Handler) to spy on Five Hargreeves but instead you end up falling for number 4, Klaus Hargreeves. You betray your Mother and leave with the Hargreeves family to stop the end of the world. The Y/n in this book is under the trans umbrella so they use they/them throughout the book.