Unicorns have become the dominant species, and with their newfound power comes new problems.
Unicorns are using their magical abilities to control the economy, forcing all other creatures to live in servitude.
The Unicorn Council of Elders is corrupt, using their influence to hoard all the sparkles and rainbows, leaving the rest to live in a dull, grey world.
Unicorns as Overlords Unicorn Privilege and Oppression Unicorn Exceptionalism and Its Dark Side