I'm glad you both enjoyed
When I was considering Aranwen's background and personality, I saw that the entry for her age was about 170, approaching two hundred years. That is a long time to cover, and for a Syl that's long enough to potentially outlive old companions. I realized she had felt loss, something that in the Sylvari kingdoms is something of an unusual concept for them. One of those things that is mentioned as a possibility, especially in more military establishments, but never really thought through fully. This informed her personality, kind and needing to surround herself with allies whom she could share in their determination and smiles (and perhaps passion). Her personal code as a bladesinger informed her determination and desire to do good.
Originally, I came to the conclusion that it might have been an old adventuring party Aranwen simply outlived. When approached with the idea of this prequel, however, I could see her with a much deeper connection, and resentment, for Sendria than I expected. I went deeper, to her more distant past.
In my mind, I saw Aranwen didn't excel in her training. She was determined to succeed in spite of her failures though, and met Saeriel much the same way. As she was originally a seer and more artistic, Saeriel likewise didn't excel, and so they were often paired with and noticed each other. Through each other, they were able to get through their training and succeed.
Saeriel's death in Sendria is ultimately the largest factor in Aranwen's personality and motives. At the start of the prequel, she still feels as though she is in mourning. The song she was singing alone being a funeral song
Incidentally, there's a different song that feels appropriate to her initial state in this prequel...