There is a girl that changes appearance when near someone. If she is within a 1.5meter radius of another human being she will adapt their physical attributes. Her skin will change, not just the pigments that make up skin colour but also the age, the number of freckles, wrinkles, scars, tattoos etc. Her hair changes to match theirs, length, colour, is it dyed, is it clean etc.
She always wears a large trench coat when she leaves her house, especially if she will be near many people. In a crowd, it becomes really difficult to remain anonymous as she is constantly changing to match the person closest to her.
She mainly lives in hiding, but it gets really lonely. It is difficult to form a romantic relationship with someone if you cannot be physically close to them. She does a lot of online dating. She is heterosexual, but will only ever be able to be in a same-sex relationship if she wants to be closer than 1.5 meters to her partner.
Until one day she meets someone who has a similar power to herself...