Just doing a search on this site pulls up lots of discussions already about aggressive roosters. It seems that some people have had success establishing their "alpha roo" dominance over the rooster, and sometimes it doesn't work and they have to be removed. If he's drawing blood, I'd say he's already had his chance. But if you want to give it a try, a few things to do are not let him mount the hens in your presence and push him off if he tries. Also, if he charges, pin his head down to the ground and hold it there for a minute, just don't let yourself get scratched or bit! This is just from what I've read, though. My roo is very friendly, thank goodness!