You were Mariah's older twin by 3 minutes. You two had a close relationship, but since she started working with DIO, she left you and went to kill the crusaders.
Usually, you felt very lonely without her, because you mostly had spent time with her. Even though she may seem like a bitch, she loves you and cares about you.
Today, you were in your home, watching TV or something, when unexpectedly there was a knock on the front door. You didn't expect any visitors, so you looked through the keyhole to see how's behind your entrance. There was your sister, Mariah. She was terribly injured, as if she was smashed between two vehicles.
You quickly opened the door and Mariah's eyes softened a bit. "There you are! I thought you weren't home." She sighed in relief and added. "Will you patch me up? It's a long story..."