Any chicken of any breed can go broody. Some may be more likely than others, but in the end, it's an individual thing. I have a black Australorp at present that's broody. A black Orpington would be pretty unusual; I wonder if you have a black Australorp.
Just because i have the option of getting a black orpington or a light sussex next year wich will all ready be broody but i will have to hope that the orpingotn will