So let's say that there's a guy who has acquired a reputation in some various circles as being bad news when it comes to women. This guy, it's said, goes to bars and takes drunk girls home, where he has sex with him without verbal consent, when the ladies told him they wanted to leave as he was taking clothes off. None of the woman physically fought back significantly.

The crucial point is that I'm hearing this stuff from various people who aren't connected - women who don't know each other are talking about the same bad experience. This makes it highly unlikely that there's any sort of conspiracy or whatever against this guy - for whatever reason, quite a few ladies are having a bad time with him, and I worry that the pattern will continue.

I happen to be aware of what these women have said, but none of them have gone to the police. However, they feel that he took advantage of them when they were drunk and had sex with them without consent.

Leaving the law out of it (since there's no proof of anything, just he-said, she-said), my question is: do I do anything in this situation? Do I talk to the guy? Warn him? Give him advice? Talk to his friends? What do I say? How can I respect the fact that there are no real accusations and nothing is proven, without dismissing the trouble he might get into?

Thanks!