It really depends on the person. But speaking of being abusive or dangerous, people with BPD are far more dangerous towards themselves than to others. Unless the borderline has some other underlying issues such as antisocial personality disorder or mania, they are generally not harmful to others. There are some cases of borderlines driving recklessly or under the influence because they don’t care whether they live or not which does put others at risk, but most do not do this. Some can lash out at others by throwing chairs or whatever, but they are more likely to take their anger out on themselves and not others. There might be a slightly elevated risk of borderlines being violent as it can often cause intense anger, irrationality, and impulsive behavior. However, as a general rule, it’s best to put some trust in others until they give you a reason not to. A person being a borderline doesn’t merit a reason to not trust them, as the vast majority are harmless to you.