I believe we meet some people in life for a reason. I am talking about good people and average people. But what about bad people? I am not talking about the worst people, but about people who do pretty bad things. For example, say a bad person has a bad time or goes through a bad experience. Are we meant to help them and get involved or stay away?
It depends on the situation, and it is hard to give a one size fits all answer to such a question. In general, though, if you can help them, and what is bad about them will not affect you negatively, then you should help them. However, if helping this person is detrimental to your neshoma, because you will learn bad middos from the person, or if the person will cause you to do avieros, then you have to protect yourself, before helping them. For example, a person who is strong in their emuna, and will not be affected by what the other person will say, etc., or if the person can recognize the other person faults, and is strong enough not to be affected by it, then he should help the other person. Otherwise it might be better to stay away. But to reiterate, each situation has to be assessed on its own.