Every one thousand years, alicorns release a pheromone that makes everypony around them become obsessive snugglers, and since this is Twilight’s and Cadence’s first time, Celestia summons them to Canterlot. Upon their arrival, Celestia is horrified to see her sister magically seal them all in her bedroom, but she is quick to discover that being locked in a room with three snuggling-obsessed alicorns isn’t that bad.
Edited by Ponysopher