A real mystery!!

I shall start at the beginning because this is making absolutely no sense!!
About 2 years ago we purchased 4 RIR pullets. They were well feathered out and so cute. Well they have turned out not to be so cute. They started attacking my 3, old cochins and my old white leghorn rooster so we separated the rooster and 3 hens into another run and coop. They are doing fine now.
In the mean time the RIRs grew and started laying. But then I begin to notice that I was getting some fertilized eggs from the RIR. Not many but about 4 over the last few weeks. I was beginning to think Henry the old rooster was doing tricks through the fence! LOL!
Then 3 of the RIR started looking all pecked. Then all of a sudden one of the RIR's started riding the others and then the other day when Henry crowed his 3 note crow this RIR tried to answer with the same crow but it was a very weak try.
I swear this has to be a late blooming rooster but it doesn't look like a rooster at all. It looks just like the other 3 hens. And my husband swears it was laying eggs.
Has anyone ever had a situation like this??
Thanks for any comments. They would be very welcomed.