Big Hero 6 The Series - Season 2eps12 -

Discuss how impacts her relationship with Hiro.

As the first part of a multi-episode arc, "City of Monsters: Part I" effectively builds tension. The threat is no longer a single villain like Momakase or Supersonic Sue; it is an environmental and biological contagion that the team cannot simply punch or blast away. The episode concludes by setting the stage for Liv Amara’s ultimate plot, raising the stakes from local crime-fighting to a full-scale survival mission for the city.

A major highlight of this episode is the reluctant yet effective partnership between Hiro and Karmi. Historically, their relationship was defined by academic rivalry and Karmi’s humorous obsession with Hiro's superhero alter-ego, "Captain Cutie." In Episode 12, this dynamic matures as they are forced to treat a victim overrun by parasites. This collaboration humanizes Karmi, moving her beyond a mere rival and positioning her as a peer who shares Hiro's drive to use science for the greater good.