i hatched 3 chicks and one turned out to be a hen and the other two roos and they all look like their sultan dad, but we have just had to get rid of the roos because they wont stop trying to attack my older cockerel. our older cockerel was badly hurt on one side of his face and was absuloutly terrified of the younger two. but now he wont stop having a go at our hen and trying to have cockerel fights with her, but she just backs away. i think he thinks she is one of the younger roos and he is trying to get her away. she isn't laying yet, bur if supposed to any day soon. also our cockerel is very crazy and doesnt think strait, we think he may have some kind of brain problem, which is why he doesn't realise she is a hen! so will he stop any time soon and will he badly hurt her?
I don't have a rooster. But if that happened I would put down or move the rooster to a different pen.
What you are seeing is the pecking order trying to sort itself out after being shaken up by the loss of two of its members. Since your remaining cockerel was dominated by the two you just got rid of, he's now trying to move up in rank by challenging the hen. It sounds like she isn't interested in fighting him for rank, so he should be moving on to another target soon. As long as there's no blood shed, I wouldn't worry about it.