Board Thread:Off Topic/@comment-24993958-20160225194034/@comment-25396609-20160315005011

mary sue is a catch-all term for several character types which are universally undesirable. They are most often self-inserts, but a wide variety exists within the spectrum.

Common traits are;

excesive or overly complex weapons for the setting

wings (angelic or demonic)

being in a romantic relationship with a canon character

being a direct relative of a canon character

being grossly overpowered without a legitimate reason being given

unique powers that go against the rules of the setting or belong only to a specific character (for a RWBY example, having two semblances would count, as would being a maiden in the present day. being a maiden from a past generation is iffy.)