K so I thought long and hard about what I think on this.
There are a lot of women in league, and the majority of them take absolutely no shit from anyone. Illaoi, vayne, Diana, Fortune, Leona, xayah, Akali, sejuani, lissandra, Cassiopeia, Katarina, riven, Camille, fiora, irelia, kalista, Evelynn, Elise, Kayle, Morgana, shyvana, Caitlyn, nidalee, Annie, Sivir, Vi, zyra and rek'sai are all examples of women what would gut you where you stand if you ever crossed them. The majority of them are incredibly aggressive, or deadpan serious.
The light side of the spectrum is much smaller. Nami, Janna, Ashe, anivia, tristana taliyah, lux, Lulu, karma,and soraka. Ahri is about as neutral as you can get.
Now we have Sona. All we know right now is she was an orphan, adopted by a royal family in Demacia, and she has a magical instrument that is drawn to get even if you separate the two. She is also mute. None of this really explains any form of personality. Let's move on.
Her quotes: she is very calm throughout the game, never makes a threat or sounds angry or manipulative like many other champions. She is easygoing, peaceful, and encouraging.
Her spell names: they are also very benevolent: perseverance: to work hard, she takes away your pain and encourages be you to keep pushing forwards. hymn of valor:. A hymn is a religious praise or poem, and valor is courage or bravery. Her hymn encourages you to be brave in the face of danger and rewards you for it. Song of celerity, celerity is swiftness or speed, and it is a very euphonious word. She encourages you to keep moving towards your goals with her song. Finally the crescendo. You see it as forcing people to dance to death. I see it as overwhelming someone with such happiness, they dance even within the thick of battle. She exudes The goodness of music. A way to tie hearts together.
Her muteness: you're right, just because someone is mute, doesn't make them passive, nor do I feel that "passive" is a very good description for any champion. It seems as though you're only trying to describe their antics in bed. I do, however believe that Sona is definitely not malicious or aggressive. I think she had seen a lot of bad in her life, and has been unable to communicate it or help others because of her muteness. I feel that, at the point we see her now, she had accepted that no one will hear her speak and instead tries her hardest to support people in hardship through her music.
I think Sona and Janna are similarly benevolent champions, and that Sona has a good heart. She's playful, given her joke, and admonishing when necessary given her taunt, but I really don't find her to be aggressive, violent, or manipulative for her own ends.
And I'm very pleased by that. Not every character in league has to be a kick-ass bloodthirsty warrior, or a manipulative schemer, sometimes you can be someone's champion by supporting them the best way you know how, in Sona's case, her music. Ivern is proof that a genuine good heart can make someone a champion, and I feel like Sona embodies this as well.