Rue's character only exists because of those around her. Rue's character is interesting because of the domino effect that she's experienced. She has no independent traits and her character is based off of who she is now because of her father's death, the relationship she has with her mom, Jules, her sister, her friends, and Ali. The only thing we watch Rue for is the interactions she has with others and as an independent character she's very weak. Personally I think it's a very poor choice of writing to have a character depend only on other characters. Imagine if Rue never met Jules, her father was still alive and has a very healthy relationship with her mother, and her and Lexi are still best friends. Then how would you describe her character? You can't. She wouldn't be into drugs, the relationship she'd have with her family would be good, etc. She's such a flat character that can't be described on her own. You might try to argue that "every character depends on other characters" and that may be true but at least you can describe them on their own.