Surprisingly the very first Undertale fanfic of its kind, Alphys VS Undyne is a short but very sweet satire story whose main purpose is to explore the rather simple yet surprisingly entertaining concept of "what if Alphys' and Undyne's relationship with each other were to suddenly grow into a rivalry?"

Clearly lacking an actual plot, the story is instead formatted into a series of publicly televised, made-up-right-on-the-spot contests that Alphys and Undyne decide to hold against each other as a way of settling their differences and determining which one of them is truly a better character than the other. These contests range from simple things, like playdates and kart racing, to literal verbal wrestling and one of the most disturbing fanfiction giantess scenes in recent memory. Although it may not sound like much, this simple yet effective premise leads to a wide variety of moments that are equal parts endearing and humorous, albeit with a markedly adult edge at times.

However, for all that its seven delightfully amusing chapters are worth, this would merely be an average, forgettable fanfic if not for the infamously ludicrous scene that takes place in its Chapter 4-6 portion, in which Undyne shrinks herself to the size of a small ant and promptly begins indulging in Alphys' now-comparatively-massive size in a blatant parody of giantess fanfiction that contains over seventy different fetishes including but not limited to:

  • giantess
  • feet
  • goddess worship
  • bestiality
  • strip teasing
  • mind control
  • public humiliation
  • ear invasion
  • breastplay/feeding
  • pornography
  • mouth/vaginal vore
  • urination
  • cuckolding
  • fellatio
  • tickling
  • torture/sadism
  • bellybuttons
  • voyeurism
  • tentacle rape
  • earwax
  • toe jam
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