Why is my rooster doing this???!!!

I have a flock of approximately 43 birds, of which 13 are roosters (STILL trying to find a home for the RIR boys) and my biggest rooster of all is suppose to be a Cuckoo Maran boy, however my boy is more white than Cuckoo patterned, so I think he might be a mutt after all. Anyway, even though he is the biggest boy, he is the lowest in the pecking order. His behavior reminds me of a very selfish child. He will pound the other birds into the ground in order to be the first to get treats, and while I have learned to throw his treats in one direction and the other birds' treats in the opposite direction, he has one behavior that is blowing my mind. Ok, NONE, and I do mean NONE of the ladies are interested in Mystery (that's his name) at all. Not a single hen wants anything to do with him. He has tried to mount them and they all run screaming. But it's not the hens that he really likes to mount, it's my white Bantam Cochin Elvis! To clarify, Elvis is ALL boy. Mystery has grabbed him several times and mounted him and poor Elvis screams until I come rescue him. The dominant roo in the flock is my bantam Barred Cochin Buddy, and he gets almost all of the ladies. Almost. A few of the ladies like some of the other boys. I feel bad for Mystery, however I am beginning to wonder about him? I know, could be that he's just trying to establish himself as higher in the pecking order, but he seems to, ahem, really "working over" Elvis, if you get my drift. He targets him at least a few times a day. It's like when the urge comes over him, he goes looking for him, and well, you know the rest. The other day it became a Maran sandwich, as my daughter called it. Mystery jumped Elvis and Buddy mounted Mystery! Not exactly a sight I wanted my kids to witness, but well, they saw it. I know that was a dominance thing. So I am wondering, will Mystery always like other roos, or will he begin to actively like the girls and want to only mate with them? What I have in my coop are primarily bantam Cochins but I also have Silkies, a Black Autralorp, 2 Sexlinks, 4 SLW's, 2 Americaunas, some little bantam mutts, and the other roos that are his age. I have 6 bantam BO's, 3 Frizzles, and 5 standard RIR's in there too, but they are only 13 weeks old. My birds are almost 21 weeks old now. If it matters at all Mystery was the last boy to start to crow and just started like the day before yesterday. He's been mounting Elvis for about a week and a half now though. Any input anyone can give me on this behavior would be much appreciated. Thanks.
I don't have any recent pics of Mystery, but here are some of him when I first got him when he was about 8 weeks old. Here he is:







He's suppose to be a purebred Cuckoo Maran. I got him in a trade and I chose him because he was the most stunning chick in the brooder. He isn't snuggly but he is very gentle once he's been caught. Anyone this he is a Cuckoo Maran? He does have pink legs and a nice, big comb now, and his blue eyes turned to a yellow amber color. Could his breed play into his behavior at all?