Let's discuss the more obscure details of Kat and Emmett!

By which I mean: • Minions • Icons • Backgrounds • Why will the two have a rivalry? • Costumes

For Kat, I think the Minion will be Raven. The icons could be just pictures of the main characters and some Nevi. The backgrounds could be some Rift Portals or Planes, maybe the cat which I've forgotten the name of. I think Kat will start a fight with Emmett for making fun of her, or her cat. As for costumes, I'd say they will just be the Gravity Queen costume, her school-girl costume, and if they do a third one then maybe the Maid costume.

As for Emmett, I don't have any idea.