Bianca has been a big sister as long as she can remember, and her dislike of eavesdroppers may stem from her years of looking after her little brother Nico by herself. While Nico mostly sees that she's strict about age ratings for movies he watches and that she sometimes scolds him, she does honestly want the best for her brother: She actually listened to Nico's rants about his Mythomagic card game, and will disobey orders for him any day. As much as she wanted her own life and friends, free of responsibility to him, she did not leave Nico until she found someone who would look after him to the point of risking their life for him.
Her attachment to Nico is her downfall, and is perhaps her "fatal flaw": Children of the gods are known to have fatal flaws in their personalities, and for a child of Hades like Bianca, "holding grudges is dangerous (...) it is our fatal flaw". While Bianca's kind heart means she is generally forgiving and does not blame Percy for her death, she is extremely attached to Nico, and likely has the potential to hold grudges, especially as at her canon point she has not yet died.
Bianca started out with a low weirdness threshold, figuring that people talking about concepts she didn't know about or thought were fictional were nuts and fainting when loaded with too much of the unknown at once. However, she has a healthy sense of curiosity which has raised her weirdness threshold so that she quickly gets used to things: Within a couple of days of learning she's a demigod and then gaining eternal youth, she "feels calmer somehow" as if "everything seems to have slowed down around me" and has no problem with this, she gains a healthy respect for prophecy, comfortably calls the goddess Artemis, whom she'd thought a myth, "Lady Artemis", and says that "being a Hunter is definitely cool". As a new Hunter, Bianca is not quite confident in her abilities yet (though she is learning to be more confident as a person, now able to look people in the eye when talking to people) and is uncompetitive, not minding losing at little contests considering she's just learning.
Her abilities aside, Bianca is a gutsy kid: Even when she's scared she'll demand to know what's going on, not only of her apparent allies but even of her enemies, as she prefers to know what's going on around her and think decisions over. She tries to stay aware of her surroundings, especially if it looks like something's going wrong, and even when she's in danger herself, she'll try to warn other people of the danger, non-vocally if that's what will help them get away. Despite her desire to escape the responsibility of sisterhood, she does take responsibility for her mistakes, and is willing to risk her life to fix them. She calls things like she sees them, whether that's answering her own questions as she figures things out aloud, or stating truths that other people are uncomfortable with.
However, she is not nearly so good at dealing with things she is uncomfortable with: She tries not to think too hard about her fuzzy memory on her past before two years ago, and would rather change the subject than talk about it. Though she's slowly growing more confident, attention makes her shy again, and she also goes quiet when people in charge are arguing, rather than try to break it up. Having taken a vow to never fall in love and be an eternal maiden, she's awkwardly silent around boys who aren't her brother, though she may eventually comment on something trivial.
