I have a black and and orange occi. I introduced them at the same time as juviniles. They were the first fish I put into my 90 gal
tank. They paired up immediatly and have done so for 6 months now. They are rarely more than 6" appart.
I did ALOT of research before doing this. I knew it was a good possibility that they would not get along, but they did - and still do.
Sometimea it just depends on the situation and the fish. You just never know. My yellow tang is the head of the pecking order in my tank, but will back off of a clip of nori to let the black occi get a nibble in - then resume his eating.