It's called "the royal treatment" because that is what she was ordered to give the merchant (first guy she fucks in this chapter) in the pages prior to the start of this chapter by her master (old guy she blows).
The master started dabbling in sorcery and summoned and bound what he thought was a succubus. There is indications that she isn't a succubus but she is an outsider from another plane as per the dialog when she is just summoned.
She loathes both men in this chapter but is magically compelled to obey.