What Is So Appealing About The Bad Boys?

This is the second blog I've posted on here. I'm not much for blogging but I found the responses from my last blog helpful, so here goes nothing? I guess this question is more for the ladies but what is so appealing about the bad boy? If any of you remember me from my last post, I was having some issues with a best friend of mine who I decided to start dating. Well things just didn't work out for a number of reasons. One of those reason is her ex's. Now she says that there's nothing going on, that she has no feelings for him. Yet she'll hang around him and will not hangout with me. Now her ex, he's a real piece of work. He's been physically and verbally abusive to her. Even when me and her were just friends and I was supportive of their relationship, he didn't want us being friends. I even called her a few weekends ago and she out with him and some couple they used to hangout with and he answered the phone saying, "Jessyca doesn't want you to call her anymore." I talked to her about this and she swears she had nothing to do with it and that she talked to him about it. She dated this guy for two years and she finally broke up with him when he body checked her into a wall. Yet, for some reason she thinks that there's some friendship there that she needs to save. I don't quite understand. I've always been by her side through the bad times with this guy and yet I get cast aside. We aren't really talking too much now. Our friendship is just kind of falling apart. So once again I will ask, what is so appealing about the bad boy?