Banshee is an odd case. She’s timid and soft spoken when it benefits her, willing to let others be silly or tease her in good faith, but past that she can be mean, at times genuinely scary, putting her shadowy limbs and ear-splitting voice to good use. As long as she’s not pushed, one doesn’t have to worry so much. She’ll even take ridicule to a point, but you don’t ever mess with her friends.
One may see her as manipulative, drawing you in with her cute demeanor and aura of kindness before taking advantage of it emotionally, but she doesn’t show any malice in this. She’s not trying to push people away - sometimes she just lets the ghost out.
It is expected for others to be wary of her, and she is well aware that she can be a bit mean. Keep her true persona in mind, however, or you may accidentally be on the wrong side of her disguise before long.