For how long would you be willing to put up with a blatant Mary Sue?
I have a character who, at first glance, seems like perfection incarnated: she's rich, drop-dead gorgeous, nice, kind, noble, generous, super-intelligent, saves stray puppies and lost hugry boys from imminent death (literally), and has kewl powers and the whole friend-of-everything-living shtick going on. Most boys want to do various NC-17 things with her, and most girls hate her for how perfect she is. Typical Mary Sue material. Now, for most of the story she's just a supporting character and not anywhere near the focus of the novel, but it turns out that the whole 'nice, kind, noble, and generous' persona is really acting, and the rest of it--beauty, powers, intelligence, etc.--is really the silver lining of a 'deal with the devil' sort of bargain that requires her to constantly sacrifice people whose souls have specific properties (which means the MCs) or else her powers vanish and her body starts rapidly rotting and falling apart. In fact, she's been manipulating all her friends and has saved the 'lost and hungry boy' just so she could take advantage of his loyalty and raise him into her own personal bodyguard and get him to sacrifice his sister eventually. Basically, she's one evil, rotten bitch (literally).
Now, what I'm scared of is that, while she isn't in the limelight at all, people will hate her for her Mary Sue-ness and abandon the story before they realize that it's all really a hoax. So I've been wondering, for how long would you put up with such a character before giving up on the story alltogether?