I came up with Duncan's younger twin sisters: Katrina and Emily. They were born on June 21st, and they're both 15. Emily is one minute older than Katrina. They are identical twins.
Emily is goth, and has quite a personality. She is smart, unique, and likes to design clothes. She wants to fasion design when she grows up. Yes, she dresses goth, but she doesen't act goth. She's happy and sweet, but she also gets sad. On the other side, she sometime accompanies Duncan when he's pranking, or she pranks by herself. She is single. She beats up nerds. She's a D+ student. She wasn't accepted to a college yet, but she doesen't care.
Katrina is a happy, popular, beautiful, and unique girl. She's one of the most popular people in school. Her siblings hate her, but she doesen't care. She's in her own little world. She wants to be a singer/artist when she grows up, sience she loves both very much. She was accepted to the New York School of Visual Arts. Although she's popular, she isn't snotty. She even gets the indie kids to be cool. She has a boyfriend, Danny, who she just dumped. Shegets high B's and low A's in school.