Now comes the part where someone interprets what's written between the lines so that the rest of us don't have to.
Parsee was a god who ended up wandering the land of the dead eating people. Yukari transformed her into a jealousy-feeding youkai, giving her a second life. (Still a bridge princess, as I understand it, just her nature was changed, god to youkai, perhaps mirroring how the stories of bridge princesses changed in real life.)
Despite that, Parsee still has some non-youkai-like qualities.
Parsee wonders what it is Yukari wants that she needs a youkai to manage jealousy among the humans, in order to keep it from erupting into the open and causing conflict.
Yukari wonders why Parsee describes Gensokyo as 'make-believe'.
I can interpret the "make-believe" part. She could be implying that Yukari has given herself too much power in this "make-believe" world [partially] of her own creation (being able to play with people's lives as she does). She could alternatively be implying that Gensoukyo is unsustainable, and eventually this world ruled by youkai will prove to be nothing more than "make-believe" play that is inevitably interrupted by reality.
I dunno, I'm tired. Don't take either of those too seriously.
You're a youkai through and through, bridge princess.