My rooster came in as a 4 month old with my 6 month old girls, one brooding a batch of chicks that were only a fews old. He was very cautious when I first put them together and the girls wouldn't let him anywhere near the flock so he hung out in the woods. The lowest hen in the hierarchy really pestered him when appeared. It took the girls about a month to accept him into the flock and another month before they'd let him have his way with them. That said, my chickens free range so if someone is being picked on they have plenty of room to get away and lots of places to hide. He was originally a run bird, so he was a bit daunted by the open sky when he first earned his freedom...thus he hid in the woods or the coop. If your birds are in an enclosed area, I can't help; but I imagine it would require a lot more caution and vigilance.
