First hellish Halloween!

What if a weird Sunnyhell Halloween happened before Buffy? Full of spelled costumes, sugar high kids, demons, and frazzled demon hunters! What would little Xander, Willow, and Jesse have dressed as? And how would it have affected their lives as they grew? Maybe have this Halloween explain some of their quirks? Like have Jesse be Pepe Le Pew and Cordy the pussycat he woo/chases? Or Willow was Batgirl or Poison Ivy? Maybe Xander was the Joker or Ace Ventura pet detective?

Would like the kids to cause havoc! Would like their ages to be 5-10 but don’t...

Inuyasha/Buffy or some other magical world maybe Harry Potter?

A spell or something goes wrong now one of the Scoobies have a new demon pet. It is possessive and protective of its master. What will the scoobies do? And is it looking more human as days go by? It's powerful and seems to be rubbing off on his master.

Things needed: A demon pet of a scooby that is not Buffy.
A needy pet with weird eating habits.
Pet magical or demon.
Pet mimicking others.
Pet following Spike because of his cool duster and the way he walks.
New pet taking things from others...