My thoughts

Ruby only knows the Ai she saw on tv, that Ai was vibrant, joyful, strong, and unbreakable, she gave a sick girl like her hope and dreams and the escape from the cruel reality that she had been abandoned by her mother. Ruby died at a very young age and as she said the only lights in her life were sensei and Ai, although she was reborn as Ai's daughter, we must remember that she died young and she would not be able to fully comprehend the multitude and complexity of emotions hidden in Ai's smile and laugh hence her image of her mother is one of perfection and unshakeable resolve. This Ai is not how Ai always was, Ruby need to understand the person behind the idol and the emotions that underline her every action so that she can really see the Ai that Ai desperately wanted to rediscover.

Aqua on the other hand knows this, but it is no use telling Ruby directly because she must discover it herself to grow as an actress and also to gain an awareness of herself and the core of her character and personality. This must be her discovery and i think Aqua understands this. We don't know much about Aqua's past life from his view hence his ease of descent into psychopathy and manipulation cannot be fully explained, what we do know is he has a firm and deep knowledge of human behaviour and emotional complexities unlike Ruby and to him she is not only his sister but a patient whose well being he must place above all else including his own such that even though he knows he's falling apart he doesn't care.

Ai is a character whom we know so little about and we are still discovering, but we know she is an expert at lying to herself due to her occupation. She is confident in her appearance and ability and is a hard worker who polishes herself constantly so she can shine above others. She understands and takes in all the negative emotions and feelings other have towards her but she doesn't rank they highly, instead she continues to strive and doesn't stifle her growth for the gratification of other people. In this sense she was perfect, unmoveable, and unbreakable. She knew herself well and her inability to understand love and she battled with these thoughts and emotions frequently but she is also an expert at brushing aside issues like this hence its only when her kids are born that she really focuses on this issue as alluded to by the opening song and the story itself.

All the characters have had traumatic experiences as part of their job or as a consequence of this, and this had shaped their lives and affected their decisions in profound ways thus giving each character in the story an ethereal yet realistic depth and touches on key points in our society with focus on the reality of idol life.