From reading your other stories I had always pictured Madame Hyun as being a lot older and rougher/greasier than these idols would be. Usually in real life Madame's like these were people that had been in the business a really long time and clawed their way up. Heechul I think of as an exception because of who he is, plus the world he makes for his clients is the complete opposite of the gritty underwold he's used to. I just think it would fit in better with the story to have someone middle-aged and starting to look his age. It could be the reason he hates Heechul so much, he has everything physically that he doesn't anymore.

v What she said.
I don't think it really matters if you make someone mean who isn't in real life. Sometimes we have to alter an idol just a bit to fit the part. It doesn't have to be exact.

i think an idol would be better... and we love all these guys so its ok.. but yeah... whatever^^ im sure it'll b good anyway!

Nooooooooooooooo make it someone we know >< OC's are difficult to envision, and often hinder the fluidity of the story~