These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Mary Sue: Fei Lee. All the boys wanted her (at least up until they get to know her) and she's powerful, causing many reviewers to complain that she's too perfect. Another would be Keeper, who's so powerful that one reviewer announced he won't be reading the story anymore solely because of Keeper even though the chapter was of Keeper's last appearance.