No, Grima probably wouldn't rape Eowyn, there you're most likely right, Cibbwin.
But I disagree (again) with the idea that Eowyn would 'beat him to a pulp' if he ever tried it. And you can read just about any of my other posts & get quite a few reasons why I think it's silly that Eowyn could beat him in a no-swords-allowed-fight.
