The Following is the third in a series discussing the Mary Sue character type.
Little Miss Mary Sue is most often created for fanfiction, meaning she is inserted into preexisting book, movie, or TV show universes already populated with characters with established relationships, goals, and conflicts. In the hands of an experienced and skilled writer, original characters can be brought into a universe’s existing social structure with a believable amount of disruption and fill a role in the plot which is important but still balanced against the canon characters. As far as Little Miss Mary Sue cares, however, anything that isn’t about her can go take a hike or die in a fire.
One of the things Mary Sue provides for her author is wish fulfillment. Mary Sue has the looks and fashion the author desires, and also the opportunities for adventure and romance the author cannot have. The fanfiction which Mary Sue inhabits exists solely for the purposes of allowing the author to live out their wishes to be part of a fictional universe, and usually to hook up with a particular character, and so Mary Sue becomes the center of everything. This can manifest as simply as isolated scenes which just so happen to involve the author’s chosen characters interacting with Mary Sue in the desired manner (nevermind if those characters are in a canon relationship or would even want to associate with people like Mary Sue in the first place). At its worst, however, Mary’s need to be the center of attention can warp the very fabric of reality.TV Tropes calls a Mary Sue who, above all else, dominates and warps stories a “Black Hole Sue.” Like a literal black hole, this Sue has a personal “gravity” so powerful that nothing escapes her influence. She pulls characters so far out of sync with their canon personalities that they become unrecognizable and mere “plot enablers” and straight-men to Mary’s own actions and lines. Crucial conflicts and major antagonists are either shoved into a dark closet and ignored or dealt with in a single sentence so that Mary’s attempts to woo Harry Potter or Gandalf can continue uninterrupted. On the off chance that Black Hole Sue isn’t in a particular scene, her gravity still draws characters to speak only about her and to shout down anyone who dares speak a bad word about her. Mary’s abilities and rate of success also far exceed plausibility, even in universes where the heroes are predisposed to win handily anyway. Things like “one in a million chance” and “high likelihood of death” are nothing but window dressing to make Mary Sue’s accomplishments appear more amazing.