[@Natsu]

If I am to be honest - Viola would probably have a love/hate relationship with Melody. On one hand, she'd find that attitude of hers completely infuriating since it's everything she basically finds abhorrent in humans. On the other, she'd find her attitude very admirable - which is why she'd do her best to mess with Melody.

I do think Melody probably has the highest chance of at least changing Viola's own personal views of the world, even if slightly. Depends on how friendly Melody is willing to constantly be around her and how much of her bullshit Melody puts up with.